I think the point is to separate the protocol from the app. It’s not supposed to matter if you like one app and I like another, we should still be able to talk. Apple can support it within iMessage, Google can support it in their app, and 10 other companies might have their own idea about what the app should look…

Email kind of sucks hard for back and forth conversation in SMS fashion. More like “Good news, we already have this. It is called Hangouts.”