Apple developed iMessage to work around the problems with SMS and MMS, as well as decrease load on carrier networks. There is no closed ecosystem, you can still receive messages and videos from iPhone users, just at the quality your hardware and software can support.

Google later decided to come up with a completely different implementation called RCS to deal with the same problems. Rather than work with Apple on bringing an iMessage app to Android or licensing it, they instead tried to pressure Apple with a public advertising campaign to adopt what is frankly an inferior solution that doesn't even have reliable end-to-end encryption.

Your complaint is basically that you bought a Toyota and it does not have BMW's laser headlights that adjust brightness and angle automatically. You still have headlights, you just didn't spend the money to get the good ones.