SMS/MMS is a horrible experience with modern devices. It needs to be replaced, and Apple is the last holdout. Google gets to finally work to sunset SMS if they can get Apple onboard the RCS train.
Someone else mentioned that RCS seems to be more of an initiative within the US. If that’s the case and it requires carriers to make changes to there technology, then it doesn’t seem like Apple is there last holdout. Rather, is a US-centric thing.