One thing I don't understand - even if this thing had physical buttons, why would Nintendo put a screen in the controller for their new console, given the lack of functionality the Wii U's controller provided for most of their top games?
Why replicate paradigms that failed in your last console?
Presumably they think they can better implement the idea this time.
The Wii U had a lot of design flaws but it died because it took years for quality games to come. If Mario Maker had been there on day one, I'm sure things would have gone very differently. There was potential in the second screen but Nintendo was in such a disheveled state post-Wii that is was not really used properly.