RCS is just SMS experience through Google's servers, just like what you have with iMessage. It may even be worse in term of what the companies extracts from your messages. Only usage I could see is if you want to use a matrix bridge that only works with RCS, like Beeper (since Apple does not enjoy users signing in with the iMessage bridge)
Oher than that, I enjoyed RCS messages when I was a Google fanboi and did not care about privacy. It still offers a better "security" than regular SMS, but you chose to deliver your texts to Google