Therefore, in muti (cooperative or competitive), players will be blown away by the Wii U, because it will basically allow them to have two different experience in one, with two different displays (TV/Tablet screen), two contrasting control methods (motion + buttons / less motion + buttons + touchscreen), and possibly two different approach of the game itself (FPS on the TV, RTS view on the DRC). Two games in one, and you & your friends would be eager to "try the other role" and switch of controllers, some would have their favorite one and be less effective on the other, etc.
We could even imagine an asymmetrical game difficulty/accessibility, like an hardcore gamer FPS on the TV handled by the experienced guy in the living room, which will be helped by his girlfriend/little sister/grandpa that would experience a simple strategic game on the padlet, triggering some things on the TV. Another way to broaden the market, and introduce a new audience to this media.
But all these possible ideas must be well implemented and promoted. Then it won't be a problem to have people on the DRC and others with the wiimotes.