Yes, I know about disk caches and data corruption and blah blah blah. But to me, it's yet another condescending reminder of who's actually in charge of the computer (hint: It's not the user, like it was in the days of yore). You don't just turn off your computer anymore. No, that would put the user too much in control. Now you request to the operating system: "Pretty please, with sugar on top, if you're not too terribly busy doing whatever it is you're doing, would you mind powering off?"
The computer has its own agenda and agency, and increasingly the user's wishes are unimportant. We've been conditioned to ask the computer to do things rather than command it.
I don't think it has anything to do with the "good old times". It is a problem that's introduced as soon as a storage medium is used. Sure, you could shutdown your C64 anytime, but even then, if you did it while it was writing to the tape/floppy, then your data was lost. And I definitely remember having to park the hard drive on an XT before shutting it down.
In the 80's, when you were in charge of your computer, if you had a hard drive and didn't park it before shutting off power, not only could you lose anything cached but not written, but you could damage the drive itself, lose all of the contents.
This is like arguing nobody is actually in charge of their bike because slamming the front brake at high speed has consequences other than stopping. It's not that we've somehow stopped being in charge of the device rather "it's going 20 mph" means there are other desires to balance beyond than "I'd like to stop immediately".
It's a good reminder that the days of yore were mostly actually pretty terrible for user control, because we're talking about a problem that currently popular computers like this cellphone and any Linux box with ext4fs no longer have. And of course before the move to Microsoft Windows around 01991 an awful lot of people were using minicomputers and mainframes they not only weren't allowed to turn off, but often weren't even allowed to see at all. A lot like AWS.
The computer has its own agenda and agency, and increasingly the user's wishes are unimportant. We've been conditioned to ask the computer to do things rather than command it.