And actually, earlier this year, WhatsApp started using the encrpytion protocol developed by the signal folks (Axolotl) to encrypt message data, Which is super cool. (I think group chats and images are still not encrypted, or something) I wonder if in the future Signal will focus on integrating their encryption into other existing chat systems like Facebook messenger, and put the Signal apps on the backburner.
The problem I have is when these systems don't indicate whether their session or secure or not. Last time I checked, WhatsApp still didn't have it. This is especially problematic when the system has exceptions like the ones you've described. (Group chats, images, etc.)
Services like LINE also bragged about their secure chat feature, too [0] but honestly, without an active indication of whether their session is secured or not, it's fairly useless and I don't really like this "hide the complicated stuff" attitude that those services seems to be going toward...
I heard somewhere on the internet (actually /r/crypto) that after being bought by Facebook, they are cancelling or backdooring it. Sounds like conspiracy to me but then again it's Facebook...
