The thing about RCS is that no messengers seem to care at all about implementing RCS themselves. Part of that is probably because depending on the carrier, RCS may require access to certain SIM card information, which only pre-installed apps can do, and part of it is that many developers are waiting for Google to add RCS to the same API that SMS/MMS already exposes because they don't want to implement RCS themselves.
Realistically, the target demographic for their documentation is 1) Apple (who they'd happily supply with details to get rid of the green bubble problem) and maybe 2) government officials looking into antitrust concerns. In theory someone working for LineageOS can implement an RCS client, though, but for those developers I don't think reverse engineering the remaining unknowns about the protocol (mostly "what server" and "what message contents") aren't that difficult.
I'm not cryptographer, but I haven't heard any major issues from actual cryptographers about MLS. It's encryption principles seem to be similar to those of Signal. Google is actually already using MLS in their proprietary E2EE implementation.
Ideally, MLS would be combined with MIMI so that messaging apps become interoperable, but that's probably a pipe dream.
> who they'd happily supply with details to get rid of the green bubble problem
I would be surprised if this eliminates green bubbles. iMessage supports many features unavailable over RCS on Android devices. These would still be disabled and Apple needs a way to indicate a degraded feature set to iMessage users.
the issue is that it simply may not be up to them, at least in Europe. if the EU decides that keeping the blue bubbles contravenes the DMA, then the blue bubbles will go
Blue bubbles don't mean privacy, and green bubbles don't mean insecure. I would presume encrypted RCS would satisfy privacy, and would remain green to indicate it doesn't support iMessage-specific features.
iMessage is encrypted. Blue means the “SMS” was sent over iMessage and it is secure. Green means it was sent as a normal SMS. This is super helpful for non-technical people that want privacy.
Blue means iMessage, and supports iMessage features.
Green means not-iMessage and supports SMS / MMS / RCS features.
Presumably when Apple rolls this out, both blue and green messages could be end-to-end encrypted. It remains to be seen whether Apple will add an indicator for RCS (and potentially iMessage) encrypted messages. I could imagine them being jerks about it and not indicating when green messages are just as secure as iMessage, or they adjust their messages that iMessage is more secure/private because Apple trusts their own key exchange more than RCS.
I was just engaging with a hypothetical - see my other replies to siblings in this thread if you need clarification. iDevices are my daily drivers, but I don't understand all the fanboys getting triggered here
If they were functionally equivalent, why signal a difference? What's the benefit, you think? I'm not saying that they definitely would signal a difference, but in this hypothetical, if the color difference remained, it would be obvious why.
there's two doors through which the message can leave your phone... the blue door and the green door. (Ignoring the SMS tiny door)
If the feature sets of the blue and green door happen to be the same for a time, that doesn't mean a message sent through the green door is "actually" leaving through the blue... The doors are actually different (even if the feature sets are the same (for a time))
We were (originally) talking about a mystical magical timeline where the two standards converge. You can make another hypothetical, where they converge, but only temporarily, but that's a new flavor on the hypothetical that was first posed way way back where the thread started. I'm sick of repeating myself, so I'll leave the musing to those who are more invested.
Not to Google. Green bubbles were a big social shaming issue affecting the sale of Android. This is all in the US only afaik. So in other countries with a similar iPhone market share there isn’t a green bubble social stigma.
That's false. The color green is irrelevant. If the Apple bubbles had been green, and the Android bubbles had been blue, still the Android bubbles would have been shamed. It was never about the color. It was because of the SMS/iMessage feature incompatibilities.
Let me spell it out: the arbitrary color lets you identify the ones who use Android. Some people think the reason for using Android is being poor. Others don’t want to be seen as poor, because social posturing is important to them.
> Others don’t want to be seen as poor, because social posturing is important to them.
Then they should buy an iPhone if social posturing is important to them.
In all seriousness now: the green buble shows you that you’re sending SMSes which, based on carrier and/or country it can cost you, especially if you’re roaming overseeas where every SMS is 10/20/50c each.
iPhone users perceive Android devices as poor. It’s naive and biased, but there’s at least some validity based on the fact that Android devices can cost anywhere from $100 for some basic model at Walmart to ~$2k for the bendy/foldies.
What most are saying is that there’s always been the perception that comes with green messages. When I was on Android (pretty much since the first Nexus all the way to the Galaxy Fold 4), I definitely noticed iPhone users avoiding SMSing with me or in groups, and instead using Facebook Messenger because of the issues that come with group texts involving non-iOS users.
Now that I’m on iOS, I’m aware of the differences, although I don’t particularly care since so many Android devices support RCS.
Just please stop sending the text that reads as follows, it totally destroys group chats and the amount of information conveyed in a react doesn't require quoting back the entire message, eg
Liked "I would be surprised if this eliminates green bubbles. iMessage supports many features unavailable over RCS on Android devices. These would still be disabled and Apple needs a way to indicate a degraded feature set to iMessage users."
I have never seen a reaction that helped. "OK" is short, it's in plain text, and it works easily. I don't need your thumbs up. Or your like. You want to emoji, go ahead, but I'm getting older and I can't zoom in on them without blowing up general text to the same size. With more complex emoji I have to screenshot the text and then pull up the image to zoom on it to even tell what it is.
I'd silence the conversation, except that iMessage won't let you have two identical groups with exactly the same members. So both humorous and serious stuff goes into the same group chat, and it's often very time-sensitive if serious. Then three or four people start joking around, reacting to each other, and suddenly while I'm at dinner (or, my favorite, one hour into a three-hour drive) my phone or watch is going off every twenty seconds for five minutes. I can't ignore them, because one of those dings might be from someone else about something that needs an answer right now. I can't risk forgetting to turn notifications back on.
When I still used an Android phone, the max-ten-people SMS rule meant that I was missing important business information - like, for example, I found out that our secretary had cancer when she asked me for restaurant recommendations near MD Anderson Cancer Clinic in Houston. Never occurred to anyone else that I had gotten none of that.
You admit that you’re getting older, and I think that’s part of the disconnect with emojis. OK does not convey the same thing. You’re talking about having to zoom in to see the emoji, and the younger crowd already has every one memorized. The reactions may not help you but I’d say for most of us, they do help.
Fine. Is "10-4" or "copy that" or "Roger" acceptable? Because the whole point of that text, in a work context (and this is always a work conversation; I like my partners but I'm not personal friends with them), is to convey "I have received your message". And a reaction generates an SMS that is, until you realize what it is, kind of incomprehensible. "Loved '[my comment]'" makes no sense when you get it as a long comment.
> The reactions may not help you
I have trouble seeing how they help anyone. You made an obvious joke. A guy who laughs at anything reacts "HA-HA!!" or whatever. What is the contribution? The youngest member of my partnership is 40, though we do have a 33-year-old joining in a few months.
This isn't "get off my lawn", much as I do love that. It's "explain to me how it's useful for actual minute-to-minute work". I'm a physician. An anesthesiologist. I never know when the next emergency will arise, but OTOH we don't go for a sterile cockpit approach because there are a lot of conversations that have to do with the running of the day at work that aren't entirely serious (and don't involve patient care, as such; that's why we don't use the sterile cockpit method - it's more about figuring out who can let whom go to lunch, becuase you can't just leave someone under anesthesia to go eat, or how we might be able to let Dr. X operate in about an hour - personnel management is the biggest part of my on-call duties).
Well you actually make a point for short reaction standardized support.
You won't be able to alter behavior of everyone around you. So at least the software should render these interactions in the least obnoxious way by being consistent on both side.
You will always be able to ask for textual clarification. But the big win is that you won't be bothered by sub-par quoting repost.
We are 3-6 people, and our pattern is specific reaction to questions like this. "do (specific task) so I can go forward" "can someone take over communication with X", depending on what we do we react differently I will do it/it is done/please clarify. This means that if you need two people in a meeting and get two "please clarify" and two "will be there" reactions, there will be less traffic in the chat. It is more concise.
You have a hint above you need to be specific what means what, when we onboard new people we go through these things. This is a problem with ontologies you have to be specific and not allow meanings to drift.
I am not a emoji expert but this has been a way to make our chats a lot more easy to get a grip on.
We do not use Apple so do not get "Loved X" types of messages.
> OK does not convey the same thing.
Fine. Is "10-4" or "copy that" or "Roger" acceptable? Because the whole point of that text, in a work context (and this is always a work conversation; I like my partners but I'm not personal friends with them), is to convey "I have received your message".
So I had missed the “in a work context”, where I think your point is slightly more valid.
>And a reaction generates an SMS that is, until you realize what it is, kind of incomprehensible. "Loved '[my comment]'" makes no sense when you get it as a long comment.
Only if you don’t both have iPhones, and the necessary information is all at the beginning. You see “Loved” and a few words from the start of the message and you remember what you said and you know which message.
> The reactions may not help you
I have trouble seeing how they help anyone. You made an obvious joke. A guy who laughs at anything reacts "HA-HA!!" or whatever. What is the contribution?
So this answer may surprise you, but emoji reacts actually do communicate something unique, and of value. They are more subtle. They also permit the conversation to terminate after the react. In my mind, and the mind of many others, an actual message necessitates a response, and I’d see it as rude to neither respond nor react to a message. Reactions are subtle and out of hand, and you don’t respond _to_ a reaction. Using a react instead of an actual text response has a way of signaling the other user that they don’t need to respond further, that you read their message, how you feel about it, and no further information is necessary. This is incredibly useful and I’d struggle to communicate with any kind of emotional nuance in this day and age without it. More fundamentally, reactions solve the problem of non-verbal communication and body language in text.
>This isn't "get off my lawn", much as I do love that.
It gives “get off my lawn” a bit when you say you don’t see how it would be useful to anyone. I’d never try to convince you that you need to use it, but I do think you should understand the utility for everyone else.
But, I definitely understand that it’s not useful for your professional use case as an anesthesiologist. Also, wow, what a cool job (seriously)!
While acknowledging that you might not have any agency about this in your specific situation, this sounds more like a social/boundaries problem than a technical one.
If I were in a group chat with people both joking around and sending messages requiring urgent responses, I'd let them know to either cut the banter and keep the channel clear, or contact me otherwise if they need my urgent reaction. Letting people hold my attention hostage like that would drive me crazy.
I realize that I live in an unusual life vis-a-vis most HN readers. I do not work in tech, and I never have. I'm a physician: specifically, an anesthesiologist. I have always enjoyed tech, and I'm certainly miles ahead of most of my colleagues on that. But. Remote work is not possible. Relocating involves getting a new license to practice medicine (3-8 months), getting accepted by the medical staff of any hospital or surgery center you want to work at (~2 months after license is secure and job contract is signed), and all the usual stuff.
So I cannot not answer any number that isn't outside the US system when I'm on call. I can't silence the phone when I'm on call. I can't ignore messages. But we're a partnership, so there's no HR to file a complaint with when someone banters on a business channel, and I can't order them to do something any more than they could order me.
I get not being able to ignore calls (although that sounds like hell too, given how common spam calls are to US numbers), but it would really not be possible for people to agree to call you if they urgently need something?
Not doubting your description of your situation, and it does sound extremely stressful.
No, not really. I’m on call for the whole hospital, after all. Any doctor or nurse can ask who’s on call for anesthesia and get my number. Some call, most text.
So your hospital uses the same group chats for banter and on-call pages? That really sounds quite dangerous (in addition to stressful for the person receiving pages). Again, not sure if you are in any position to suggest changes here, but would an actual on-call paging system not make sense here?
There are so many apps/services available for this exact purpose that can alert (with or without sound, per user choice) through iOS's and Android's "do not disturb" mode, can call or text several numbers in sequence (useful in places with weak signal but a landline) and much more.
No, hospital doesn’t, but my group does often mix business and pleasure and I don’t have the luxury of ignoring them even if I happen to be on call.
The multiple-dial might help if we had a fixed location, but we don’t. Getting boosters or microcells in dead spots is just now happening, but the IT department could also enable WiFi calling, which they block.
It definitely sounds like a technical one if you can't make two groups, one for banter and one for serious talk so you can mute banter when it's not appropriate.
How are other people supposed to know that it's not okay for you right now because you are at dinner?
We all live in the same metro area. You might eat as early as five, you might finish as late as nine. But if you're going to use the business group, it should be about business. Banter is fine during working hours.
People get lazy and just use the "whole group" message rather than send it to those who are working today. And it's much like my problems with Android vs iOS: there are twelve people in this group, eleven of them have iPhones. They are not all going to install and use a separate messaging app for business than for personal communication, especially as iMessage is nominally E2EE. I could adapt or just be completely marginalized. So now twelve have iPhones.
Have you considered using something like Slack or Discord or (can’t believe I’m suggesting this) Teams, all of which sound like they’d be more suited to your use case?
This does not sound like an impossible stretch, works on more device types, and in the case of Slack or Teams can also be configured for HIPAA compliance (which while you don’t call it out, seems like it may be useful). Tens of millions of people use a chat system for work distinct from their personal friend groups, even if the venn diagram is a circle.
Oh, that for sure. That seems like the obvious solution I'd pick on Signal or WhatsApp, and if Apple Messages doesn't support it, it's yet another infuriating example of their "we know best" attitude.
I like Apple hardware, but try to avoid its first party apps as much as possible due to that.
What happens if you have a group with N+1 members and then remove the extra one? That would be a weird error message to write... "you can't remove X because everyone else is already in a group?"
The thumbed up reaction is useful because you can react to something specific in a fast-paced conversation. iMessage also allows replying to a specific message, which is also useful for the same reasons.
> With more complex emoji I have to screenshot the text and then pull up the image to zoom on it to even tell what it is.
...you can make the font bigger. Or get glasses.
> I'd silence the conversation, except that iMessage won't let you have two identical groups with exactly the same members
Create group 1 with coworkers A,B. Create group 2 with coworkers B,C. Add C to group 1, A to group 2. Two different chat groups.
"I won't bother to look up how to do things on my phone" != "my phone sucks."
> The thumbed up reaction is useful because you can react to something specific in a fast-paced conversation. iMessage also allows replying to a specific message, which is also useful for the same reasons.
A makes joke. B and C react "laugh". D replies with sub-joke. E, F, and G react "groan". Produce this little cascade every time a serious topic is brought up and someone makes an offhand joke as a lead-in to a serious topic.
> you can make the font bigger. Or get glasses
I have and use reading glasses. Making the font bigger is an option but I can read text just fine at that size. I can't make out the details of a complex emoji.
> Create group 1 with coworkers A,B. Create group 2 with coworkers B,C. Add C to group 1, A to group 2. Two different chat groups.
A completely non-obvious behavior (you can only create a group after you have sent the first text, see https://support.apple.com/guide/iphone/group-conversations-i... for info), and as it's late at night, I can't test it. Trying to search for how to do this turns up mostly threads about how the same group of contacts keeps showing up in different conversation threads.
> "I won't bother to look up how to do things on my phone" != "my phone sucks."
Feel free to tell me what search will show me how to make a "MyCompany - Business" and "MyCompany - Social" group without ever sending a message, and guaranteeing that Business messages always go to Business and Social always go to Social.
> A makes joke. B and C react "laugh". D replies with sub-joke. E, F, and G react "groan". Produce this little cascade every time a serious topic is brought up and someone makes an offhand joke as a lead-in to a serious topic.
iMessages/SMS is not a conversation or an email and the same rules don't apply. You don't have the recipient's attention for any longer than it takes to read the message you've sent. If you want to make a joke then make a point you need to do both in the same message.
That zoom on iPhone is a perfect Apple thing: here is a very useful feature, we will document it but never bother to publicize it, and it’s going to be buried behind a strange gesture requiring both hands (double-tap and hold with three fingers, then slide up or down!).
I can’t change the behaviors of others. And, in practice, while email isn’t really considered a conversation, messaging is. Stuff that would be no problem in a physical conversation (three people laugh) is incredibly distracting when every one of them feels compelled to note they found it funny.
> I'd silence the conversation, except that iMessage won't let you have two identical groups with exactly the same members. So both humorous and serious stuff goes into the same group chat, and it's often very time-sensitive if serious
Really? That's insane, so that means that 3rd party messaging apps literally have better UX than first party ones, as I have lots of groups with the same members for different things.
Absolutely. Apple Messages is way too minimal, for both iMessage and SMS.
As another example, it makes it almost impossible to manage multiple numbers for a given contact (e.g. to explicitly text somebody’s work phone), and the sender side is very confusing as well with dual-SIM. Apple’s implementation freely merges threads that I’m trying hard to keep separate and then still falls over with tons of delivery errors in complex situations (usually after swapping SIMs).
It all works reasonably well if you have a single long-lived mobile number and all your contacts have the same, and are using iMessage (or now RCS), since that’s presumably the reality for most Apple engineers.
Anything slightly more unusual and the thing falls apart completely and makes me wish for a Nokia 3310 (or convince my contact to switch to something more reasonable for messaging).
I don't believe this is true, but you do have to give one of the iMessage groups a name to make it independent from another group.
If you imagine that primary key for a group is its name, and the default name for a group is its participants, this does kind of make sense.
You'd expect an app, like Whatsapp or Discord or Signal, which focuses primarily on messaging, to be able to devote more attention to it than apple, which is really just a hardware company that reluctantly makes just enough software to charge 30% of all the good app's profits, and sell their hardware.
iMessage just not supporting android/windows/linux devices already makes it drastically worse than any other popular chat app.
You’ve pretty much indirectly nailed the issue: on iOS, iMessage is much more than just a “chat app”. It has an unrivaled feature set on iOS that isn’t replicable on other chat apps. The discourse that reduces it to a “chat app” is critically missing this point.
This wouldn’t mean much if iOS was a small percentage of phones. In regions where it is a majority of phones people use those additional features. In places like the US where most people are using iOS, most people don’t even realize those features don’t exist or are semi-broken on other chat apps because they don’t use them. For average people that have been using iMessage for a long time with other iMessage users, using those other chat apps feels like a downgrade.
The only two features I can think of that iMessage has which discord/whatsapp/etc don't are:
1. Automatically can flip to "do not disturb" mode when my phone is in sleep mode, and display that notice to my companion. Other chat apps require manually configuring that I think. I also suspect apple doesn't provide an API to make this easily possible for other apps.
2. iMessage makes it easy to identify the poors, the android users, and ignore them. If I exchange numbers on a dating app and get a green bubble, I can know to immediately ghost them.
Are those the features you were thinking about, or something else?
Most (all?) of the Apple iOS apps and data can be collaboratively shared, edited, etc over iMessage and it is extremely seamless with fine-grained access controls. I get people sending me calendars, notes, slide decks, documents, etc to either read or work on together via iMessage/iCloud. You can selectively share most things in your iOS environment with any other person in the iOS ecosystem. Google Apps is a pale imitation of this. And the security is tight.
I’ve never seen anything like this on any other chat app I’ve used. Most objects in iOS can be directly shared or collaborated on over iMessage, and that is a very rich set of objects. People that only use iMessage don’t even realize other chat apps can’t do some of these things.
So… attachments? WhatsApp and Signal can send those too, directly from the share sheet.
I find the iMessage implementation very clunky compared to WhatsApp. It’s trying so hard to be “minimal” about delivery status and recipient capabilities that I never quite know whether something worked or not, especially with contacts that have older devices on their iMessage account.
They use iMessage with their family and friends. They use it at work too. Some of their friends, and maybe some of their family, work at the same place. I can try to convince 11 other people who are my business partners to switch to, say, Signal. A special app used only for our group communications. Or I can buy an iPhone. I chose the latter.
It's not my choice. I'm making the best of it that I can. I wish it were not so, but it is.
All the non-tech people in every non-US country have whatsapp/telegram/wechat/line/kakao installed (depending on the country), and it seems to work fine.
It's just the US that has picked a universal messenger that doesn't work on android, every other country, the vast majority of the planet, defaults to a cross-platform phone messenger app.
Not every non-US country. Most people in Norway have iPhones, so iMessage is heavily used. They also use Facebook messenger a lot for some bizarre reason.
> iMessage makes it easy to identify the poors, the android users, and ignore them.
I hope this is sarcasm, and you're not actually that narrow minded.
It is an interesting complete marketing victory in the US by Apple though, that there is a widespread perception that you would only have an Android if you couldn't afford an iPhone. I've had an iPhone for work, it's fine. I much prefer Android and I'll stick to it, and the reasons for that have nothing to do with money. I'm glad I don't love in the US where that would apparently make me a social pariah.
iMessage's killer feature is that you can send a group message to more than a total of ten people. SMS does not officially support this.
I do not recall this being a problem in the pre-iMessage days, even with flip phones. I was on prepaid T-Mobile and had to pay for every message I received, which is the one place where I thought the US billing system had gone nuts - you could always decline to receive a phone call, knowing the number, but you can't refuse a text. I was surprised that nobody ever abused that, but they never did so on a large scale. At ten cents per text, sent or received, you communicated when you needed to, or when you had something to contribute, but one minute of voice was the same cost. One sent and one received text cost as much as two minutes of talk, which can convey a lot more information.
I can't remember the last time I sent an SMS. Comparing iMessage to SMS is not useful. Compare it to one of the (several) cross platform messaging services.
In Europe, Android is on equal par with Apple. WhatsApp is the default messaging service - it is universally installed among my friends, relatives, colleagues, contractors etc.. No-one cares what model of phone the other person has. Everyone communicates.
The protocol is open but key exchange is not: even on Android, third-party messengers can’t interoperate with Google Messages. See page 11 of that PDF.
That's true, but Google has also indicated that they're switching to the GSMA spec which is intended for interoperability.
I also doubt that Google would withhold such details from parties like Apple even if they maintained their proprietary format. Small developers would need to reverse engineer the details, unfortunately.
My question is basically whether they open it up or limit it to companies they have deals with. Reverse engineering is a risky game for a service with device checks since that’s potentially a CFAA violation and it could lead to your users getting their hardware banned.
Only Messages was allowed to support it. At the time it was written, for example, it was years after the Signal developers had asked for basic RCS support (2015) and given up on Google relenting and allowing it in 2018.
Signal has been rather dismissive of RCS in general. Of course RCS was as insecure and unencrypted as regular SMS/MMS until now, but I haven't found a sign that Signal ever even looked into supporting RCS at all.
At this point I think they just wanted to get rid of their SMS backup feature and used RCS as an excuse.
Signal was dismissive of unencrypted messaging. Google used their protocol for their proprietary E2EE system so it’s unlikely that this objection would apply if that system was open.
Put another way, if this was a Signal thing what other Android app is doing this?
None, but that issue has no mention of what you said in the other message
("Only Messages was allowed to support it. At the time it was written, for example, it was years after the Signal developers had asked for basic RCS support (2015) and given up on Google relenting and allowing it in 2018")
Because the rest of the world seems to neither care nor even notice the bubble (of either colour) i.e iMessage is irrelevant almost entirely outside North America (and that too I guess mostly USA; only among just the iPhone users of course)
I believe Canada has an even higher iOS market share than the US. Mexico mostly uses WhatsApp but I don’t text people there much. I have and use both WhatsApp and Signal routinely in addition to iMessage; no one I know uses WhatsApp within North America and only a handful use Signal.
When I worked in Europe just about everyone I texted with had an iPhone. We always use WhatsApp or Signal there by default. Nonetheless, iMessage was usually the fallback when those chat apps glitched because it is so reliable, especially compared to Signal. YMMV, etc.
What iMessage has going for it is that it is genuinely a very good implementation of a social chat app with unique features enabled by the iCloud ecosystem. I’m pretty agnostic about it, I’ve used a lot of chat apps by virtue of being more global than most, but iMessage is objectively pretty great when you stay within the Apple ecosystem. I’ve reduced things down to WhatsApp, Signal, and iMessage, which is kind of the minimum set that gets you global coverage, but if everyone is on iOS then iMessage is noticeably superior to Signal or WhatsApp. iMessage is more than just a chat app but it limits itself to that when interacting with other ecosystems.
> I don't think reverse engineering the remaining unknowns about the protocol (mostly "what server" and "what message contents") aren't that difficult.
That's hard to parse. Removing the double negation, we end up with
"I think reverse engineering the remaining unknowns about the protocol (mostly "what server" and "what message contents") are that difficult."
> RCS may require access to certain SIM card information, which only pre-installed apps can do
> because they don't want to implement RCS themselves.
Sounds like they can't implement RCS themselves even if they wanted to, not simply that Google doesn't provide an open source implementation? (Referring to app developers here, not custom ROM devs.)
They can't implement RCS for every carrier, but they can implement it for some. Others require nothing more than a network call to a predefined HTTP address over a data connection.
Although Google may dislike it, I don't believe Google's RCS implementation (the one most of the world uses) requires elevated permissions. Their activation sequence is proprietary and closed source, though so I'm not 100% sure.
Just having a base implementation for custom ROMs would be a start. Given that Google will block custom ROMs from RCS in their app (I believe because the spec says to), there is a need for an independent implementation if this makes RCS popular enough under American users.
Someone will have to inventory the activation mechanisms for each carrier to see if there really is a disadvantage. I'd start with mine, but all of the carriers in my country have shut down their RCS servers a decade ago.
I am not familiar with RCS, but considering the plethora of messaging apps available that just work, why did they choose the most complicated way for users to use it? And what do you mean it is not available on every carrier and needs SIM access?
I haven't seen any indication of that at all. There's sort of an API, but it's basically restricted to Samsung's messenger only.
The EU won't get involved unless a significant chunk of the user base uses Google Messenger. I don't think EU users will reach that threshold because most of the EU uses basically any chat app except for SMS/MMS. Things like receiving verification SMS messages still work using the existing API and I have a feeling that that represents the majority of SMS use in the EU.
I don't think Google wanted to gatekeep their E2EE implementation. They have some generic documentation about how it works: https://www.gstatic.com/messages/papers/messages_e2ee.pdf
The thing about RCS is that no messengers seem to care at all about implementing RCS themselves. Part of that is probably because depending on the carrier, RCS may require access to certain SIM card information, which only pre-installed apps can do, and part of it is that many developers are waiting for Google to add RCS to the same API that SMS/MMS already exposes because they don't want to implement RCS themselves.
Realistically, the target demographic for their documentation is 1) Apple (who they'd happily supply with details to get rid of the green bubble problem) and maybe 2) government officials looking into antitrust concerns. In theory someone working for LineageOS can implement an RCS client, though, but for those developers I don't think reverse engineering the remaining unknowns about the protocol (mostly "what server" and "what message contents") aren't that difficult.
I'm not cryptographer, but I haven't heard any major issues from actual cryptographers about MLS. It's encryption principles seem to be similar to those of Signal. Google is actually already using MLS in their proprietary E2EE implementation.
Ideally, MLS would be combined with MIMI so that messaging apps become interoperable, but that's probably a pipe dream.