You should also check Wii U pad thread. The Wii remote sucked IMO but it had fantastic functionality as a motion controller while Wii U gamepad functionality didn't resonate with anyone.
Are we also forgetting the the Wii was successful in spite of the shitty motion controls?
After the novelty wore off, no one gave a shit. See: Every third party release.
Besides, how many great Nintendo games even took advantage of the controller?? Not nearly enough to justify the control scheme.
All they had to do was make a bare-bones machine that plays Nintendo games. With fucking buttons... It's all they needed.