True, as is the case with almost any messaging service. But the benefits of RCS do include:

• Not having a government/telecom company be capable of snooping on your messages
• Branded messages that clearly distinguish real companies from fake ones, which can prevent an untold number of scams as it becomes more commonplace
• Uses more modern protocols instead of still being capable of sending over old, insecure ones like 2G.

It's purely an improvement over SMS in terms of security and privacy, and personally, I don't think users should be defaulted into having their phone downgrade to insecure protocols. It should always be an opt-in decision they have to make. (although they could definitely make it clearer that someone could enable it if their messages are failing to send with RCS)