RCS is infinitely better than the current state. Google isn't pretending it's a standard. They're trying to improve messaging between android and iphone uers. Apple won't because the current standard helps their business. It's pretty simple.
First RCS version been developed in late 00. Google had and has zero affiliation with it. What RCS today been published in 2016 and again, Google had no affiliation. Google wasn't even the first one to support RCS - it was Samsung in 2012.
Google, however, added their own extension for E2EE and started roll out with their self-hosted RCS rather than carrier hosted.
Given that RCS is mandatory in 5G networks and supported by world's largest carriers - Yes, it's an industry standard. Given that version used today is published in 2016 - Yes, it's modern. So, what's the problem?
RCS has zero carrier support (in fact carriers are trying to develop their own competing standard). Why would anyone (Apple or otherwise) buy into an already fragmented Google "standard" knowing full well that Google has a pernicious habit of killing off messaging products?