iMessage has shitty UI though. Always strange being reminded it is used extensively in US, but then I remember people in US still send non-robot-made SMS (even robot-made are shifting here to messaging platforms though)

I don't really understand... Does WhatsApp have a better UI? Why?

To me signal is the best UI, and WhatsApp looks like a child designed it. Especially with the horrid default colors and backgrounds.

But I don't really see a difference in UIs in most chat programs. There are only two types of UIs. Point-to-point (signal, WhatsApp, imessage, etc) and room based (irc, matrix, slack).

Their all so similar, I don't understand what is better or worse in Signal compared to WhatsApp.

How many people would use iMessage if it wasn't bundled with the phone ?

What's wrong with iMessage?

Nothing, but there's nothing really compelling about it either. Don't get me wrong - the unassuming system design works great for OS app - but you wouldn't attract many users to it with the feature set it has

I don't really find that a very compelling criticism, to be honest. When I think about what kind of features I'd want in my messaging app, there are really only two things I can think of that iMessage doesn't have: encryption, and the ability to easily leave a group text. Add those two things in, and I'm there for life.

On the other hand, both of these things are essentially limitations imposed by SMS, at least when one end of the conversation is not an iPhone. Both can be fixed, at a small cost in complexity, and if they did that, I think it would hit a good balance between features, usability, and architectural complexity.

But you're a fraction of a percent of users who care about this. I guarantee you 10x more people are interested in having animated stickers.