What I find most entertaining about this whole thing is the emphasis that people put on companion apps these days for particular games and even consoles.
All of the things being described for this app remind me instantly of the Xbox app, where a lot of the same things can be done.
I don't mind it so much because when I do play online I don't ever use integrated chat features because they always suck in one way or another. The biggest issue, and the reason that Nintendo would try and offload it to an extent is due to the biggest issue with integrated voice chat on consoles and in games in general, kids yelling obscenities.
If you push it to an app, you have to go through a bit more effort to get into the chat, and you're probably limiting the group to your party, rather than getting as many random people in the chat.
I don't think there's any reason why integrated chat couldn't be included from a technical standpoint, I think it's still a culture thing for Nintendo. I hope it changes at some point, but in the mean time, this doesn't bother me personally (though I see why some people are frustrated).
What I'm happy about is the fact that they're making an investment in their online infrastructure to bring it into the modern world.
If it isn't what it should be, I really hope people don't just swallow it like always. Let them know what's wrong with it, and force them to change, especially in that trial period.