RCS has been unreliable beyond acceptable limits. Chatting with people, and suddenly it switches back to SMS/MMS out of nowhere, and then back to RCS. Completely destroys any of the benefits. High quality photos and video? Sometimes it works, sometimes you get a grainy mess. Encrypted messages? Meh, occasionally. Seriously. After using iMessage, this is a nightmare. Every client should be forced to support a specific set of functions and not fallback to SMS just because.