On the one hand, Google is right - iMessage works great for iPhone-to-iPhone communication, but the fallback to the old SMS/MMS standard is a negative for everyone, including Apple customers, in all other scenarios.
On the other hand, I trust Google exactly as far as I can throw them with regards to maintaining a messaging standard or platform. They had Hangouts, which did almost everything iMessage did at the time (no E2EE but it covered everything else), PLUS it had an iOS client, and it was tied to a gmail address, which almost everyone has. Then they killed it, because reasons, so they could make a new client (Allo) that wanted some assistant integration for some reason (presumably so they could read your messages and serve better-targeted ads). Then they killed Allo, which was terrible anyway, and resurrected the husk of the AOSP messaging app as a first party proprietary thing, with new and improved carrier lock in.
It's garbage.
The solution is Signal, but getting people to adopt a non-default messaging app that none of their friends are on is very difficult. I tried before, with Hangouts, with limited success, and Google spat in my face. Never again.
Given that, swapping the SMS/MMS fallback for iMessage (and Signal, and anything else with SMS/MMS fallback) for RCS (which then falls back to SMS/MMS if you have 2g service or no data), seems like the least-worst option.
