That doesn't really address the issue, the audience for mainstream, western focused software is simply not on Nintendo consoles and hasn't been for 15-20 years.
You didn't answer the questions at all, why would people who already own a PS4/XBO buy a Nintendo version of those consoles? Why would people looking for a new console to play AAA 3rd party titles choose Nintendo over PS4/XBO?
And why should it continue to be that way? I don't think it should really, and Nintendo should try to push more for those games on their consoles. And I'm not looking at it as "Why people should choose Nintendo over PS4/XBO", but why people should choose Nintendo. Perhaps portability of the Switch is the way to go, although it'll be lacking some big games from other consoles, or maybe a standard console that can play those multiplatform games and Nintendo games is. I don't know, and that's where I'm torn. I'm not really saying either one is right.