Honestly I just want an Android iMessage app. If this forces Apple's hand that would be awesome.
In my circle in the US I don't know anyone that uses a 3rd party messaging app on either platform because that really only works if everyone you want to talk to also uses that specific messaging app. Switching depending on who you're talking to is annoying, so (people I know) don't.
It is much less convenient to be in a group chat with an android user.
I've never met anyone whose choice of instant text app is conditioned by the hardware they use.
Sure. I already have a different app to chat with WhatsApp users, Facebook messenger users, Discord users, Reddit users, etc.