And as you can see in my comment "what is Apple's motive for giving up their moat?"
Edit: I am not sure I understand why the downvote. Also disagreement should not be expressed with downvote. I was stressing that my point (and Apple's I guess) is it doesn't make business sense what Google is asking.
SMS isn't their moat, though. They wouldn't give up iMessage.
Supporting RCS (again, in addition to iMessage) would make their product better: it would allow higher quality media to be sent to and received from non-Apple users; it would allow for typing indicators and read receipts with non-Apple users; and (perhaps most importantly) it would allow - if Apple adopted Google's extensions - e2e encryption with non-Apple users. Apple loves privacy, after all.
It results in a better experience for their users, but it would not improve their business. It would lower the barrier to switching from iOS to Android. A lot of people, myself included, only have an iPhone because of iMessage. I would love if my iPhone supported RCS. But that is at least in part because it would pave the way to me being free from Apple (not that I’d necessarily switch). And that hurts Apple directly.
It also hurts them because it decreases their network effect. If people do not encourage each other to move to iMessage because RCS is more available, fewer users switch to iPhones.
Edit: I am not sure I understand why the downvote. Also disagreement should not be expressed with downvote. I was stressing that my point (and Apple's I guess) is it doesn't make business sense what Google is asking.