Would be all for it... if it was end-to-end encrypted. :/
Google (and seemingly only Google) does
allow end-to-end encryption via RCS, but "Both users need Google Messages, RCS needs to be on, and it's for 1:1 chats only." In other words, only a small percentage of RCS chats are realistically going to use E2E. iMessage, on the other hand, is always E2E. IMO, E2E is as essential for messaging applications as HTTPS is for the web.
Now don't get me wrong, iMessage is no Signal. It does have major flaws, such as being closed source and the situation where having iCloud Backups enabled essentially makes its E2E useless in certain scenarios. But the fact that it is E2E has had a major positive privacy and security impact regardless (we've seen quite a few court cases from governments and data-hungry corporations who aren't happy about it).
I really wish RCS would go E2E by default.

Although it is clearly is a major improvement over SMS, I just can't bring myself to support the introduction of any new messaging protocol that doesn't default to it. One of the biggest issues with SMS is how insecure it is, and IMO if a new protocol isn't going to fix
that then we shouldn't even bother with it. Apple certainly has multiple reasons to not get on board with RCS (including selfish ones), but they may also be sending a message that it's E2E or bust. And if they are, I support that.