My reason for wanting it is pretty simple. In a family full of iPhone users, my wife and I are Android users. Having iMessage would be wonderful for group chat, unlimited character length, unlimited photo, video and attachment size, read reciepts, end to end encryption, etc. Theres really not a reason to NOT want it.
Also, there is no iMessage alternative on Android. You have facebook messenger and whatsapp (a facebook owned company) so theres no way i would EVER use those as there is 0 privacy. There are other smaller options like signal, telegram, viber, kik, etc... But no one is EVER going to convince all of their contacts to sign up for a random 3rd party service. I understand countries outside of the US dont use SMS and so depending on what your friends are using you might have a handful of different apps just to communicate.
In the US, we primarily still use SMS, which is pure crap. Its the equivalent of using dial-up when the rest of the world has moved on to fiber. RCS is supposed to fix this, but Apple may not support RCS and so then it becomes a moot point. You also have to remember that iPhones make up less then 15% of phones worldwide. Just because they are popular in the US doesn't mean they are popular everywhere.
Honestly, its stupid of Apple to NOT release iMessage for Android. Blackberry did the EXACT same thing in the 90's with BBM. Once/IF RCS does come along and becomes the new standard, Apple will be trying to play catch-up (like BBM tried a few years ago by releasing to other platforms), but the world had moved on. If Apple released iMessage now before RCS catches on, they could completely capture every market and be the standard of mobile messaging.
