Hopefully this is just a part or peripheral of it, if anything.
Not a fan of touchscreen buttons.
Rumor: Images of Nintendo's NX Controller Surface - Niche Gamer
Nintendo just doesn't get it. Console gamers don't want gimmicks. Yeah, Wii did pretty well with the new motion-based controllers. But that fad is mostly past. And it didn't really carry over to the Wii U.
I can see where having "soft buttons" could open up a lot of possibilities that aren't possible with mechanical buttons, but then "soft buttons" aren't very conducive to feedback, which you get with mechanical buttons.