OP is a funny person. It's like saying "the iphone was a mistake". It really amazes me when people are so cocooned and egocentric that they have no awareness of what's really happening around them.
I do, but it’s all international friends—or American friends traveling. I don’t have a single American friend who uses it to contact people within the U.S.
Apple isn’t like Google...switching messaging apps every so often because none of them caught on. Because Apple has stuck with it since day one, users have confidence in iMessage enough to use it long term. Not the case with other apps.