Turn that on its head. What does RCS bring to the table? RCS brings two types of features: those that carriers will try to monetize (file transfer, VoIP, visual voice mail) and those that seek to drive "customer engagement" (chatbots, carousels, branding, quick-reply suggestions, "rich" cards).
From the Wikipedia page:
RCS Business Messaging (RBM) is the B2C (A2P in telecoms terminology) version of RCS.
*This is supposed to be an answer to third-party messaging apps (or OTTs) absorbing
mobile operators' messaging traffic and associated revenues*. While RCS is designed to
win back Person-to-Person (P2P) traffic, RBM is intended to retain and grow this A2P
traffic. … RBM is expected to attract marketing and customer service spend from
enterprises, thanks to improved customer engagement and interactive features that
facilitate new use cases. *This was the primary reason for the development of RCS by
the GSMA*.
No. Thanks. As I said, I don't really care if Apple implements RCS support in their Message app. If they do it's just one more thing I'll disable.
My take is that carriers should be dumb pipes. Voice, SMS, and data routing and that's it. Part of the reason RCS is already fragmented is because the carriers are trying to monetize it, you can bet your ass they're going to continue to drag their feet with E2EE – which is why Google's stood up their own separate RCS infrastructure.
Didn't Google Talk, Google Chat, Google Hangouts, and Google Meet all support group chats? Didn't Google Talk even allow for federation?
The problem with RCS as a solution is that you're either going to rely on the carriers or Google and Apple to host infrastructure. Requiring Apple to implement support for Google (hosted) products is ridiculous as Apple already lists Google chat apps in their app store. Requiring Apple to host their own servers to interoperate with Google's services is also ridiculous because again Apple already provides software to interoperate with Google's chat services.
Requiring Apple to support RCS so their users can leverage carrier hosted RCS is also ridiculous because that's a fancy way of saying Apple should be required to monetize their users for the carriers' benefit. Per the Wired article linked to MMS was created solely to extract money from their users (or as Wired put it to "collect a fee every time anyone snaps a photo"). I'm sure most folks who are old enough remember when SMS (which literally consumes no additional bandwidth) was a paid feature, does everyone remember when MMS cost even more than a plain SMS?
RCS may not be a cash grab by Google, but they certainly haven't had any luck in getting the carriers to implement customer friendly features. Another lowest common denominator "standard" like RCS isn't an improvement at all, especially not in the face of the freely available, cross platform messaging apps.
What does RCS theoretically bring to the group chat table?
File transfers? Google's gonna mine them or carriers will charge exorbitant storage/transfer/viewing fees.