If you're going to make the crux of your system a tablet controller, it better be a good experience.
Honestly to me the touch is far less relevant than having a screen.
I like the touch - it's good for using the web browser, for navigating Netflix, for drawing in Miiverse and for entering text via the software keyboard. However when it comes to games having a second screen (or a portable screen) is much more important than what form of touch the screen has if it has any at all.
If the screen had no touch whatsoever my game playing experience wouldn't change that much.
I don't consider it a tablet - it's a controller with a screen. With touch. In that order of importance.
At no point playing a game have I ever thought "this would be better with multitouch", nor have I ever thought "man I wish this had a bunch of iOS ports!" Pinch to zoom would be nice in the web browser - that's all I've got as far as realistic ways multitouch would make my life better.
Pinch to zoom on an in-game map? My hands are busy playing the game, I'd rather tap a button with my thumb.