It's a huge pain point to get people you communicate with to switch to some message app.
I had to go through that process and get everyone that matters on to hangouts. Months later I was still getting SMS messages because most were perfectly happy with iMessage and didn't want to put the effort into migrating over.
The fact that SMS is unlimited with almost ANY phone plan makes it a little less irritating.....
The bigger problem was having multiple apps for hangouts, messages, video calls.....
Thank goodness Google is finally consolidating some of it. I think the new Hangouts app works quite well. Though I will continue to miss the texting over wifi functionality of iMessage. That is where this idea of being on the same ecosystem comes into play......
Cell service in my house with my radiant barrier is atrocious.