This is great - I switched from iOS to Android last week, and my biggest annoyance was the lack of iMessage
For group messaging, are all of your friends still using iMessage instead of cross platform things like Telegram, WhatsApp, Hangouts, Discord, etc? If so, why?
Worst case of course, all of your iMessage contacts can be contacted over plain old SMS (Via Messenger, Hangouts, or any of the hundreds of Android SMS clients).
Now that the era of Apple being "cool" is officially over and we'll see more and more people moving to Android, I think the appeal of the iMessage "hey you can talk to anyone you want as long as they're on an iPhone or a Mac!" walled garden will collapse.
It's not surprising that people use what comes on their phone and computer by default.