As Michael Goff points out often it's simply a path of least resistance or convenience or is it
There are equally many other scenarios where you taken this easy route for friends or family etc but end up fiddling around more regardless
You travel internationally, you force Granny down the route of expensive iPhone, you buy your kids iPhone but no data plan, new friends or business contacts are not iPhone users etc etc and so on …………
I agree for some in a relatively small bubble it works well and I think there was a very specific case where one chap takes orders via Imessages and needs to combine them in to one sales invoice, this works for him
But as a whole and for most in the world it's trivia. The most popular message app in US is reported to be facebook messenger so it's likely many iPhone users are already loading additional apps to communicate. Good phones automatically load software when you swap or upgrade so for most it's a onetime install not every time you change phones