Interest in RCS is recent - newer than iMessage, which launched in 2011. RCS with Google's proprietary extensions is just another proprietary messaging app, and I am not particularly excited about it.
even so far as “patch” a fix that was created to make it possible for their customers to communicate securely with Android users.
There's no shortage of options for doing that. What Apple wants is tight control over all of its walled gardens, which should be no surprise given the company's history. They're very good at making it appear as if decisions made to increase their profits are aligned with the interests of users. It's probably even true that someone would have exploited the technique Beeper Mini was using to send spam if Apple hadn't closed it.