I think some developers simply don't want to compite against Nintendo in their own console. Maybe they feel that if they release a game will be eclipsed if at the same time Nintendo launchs Zelda or Mario (or something like Wii Fit or Wii Sports Resorts).
Proud to be the first cool Nintendo fan ever
Number ONE Zelda fan in the Universe
Prediction: No Zelda HD for Wii U, quietly moved to the succesor
Predictions for Nintendo NX and Mobile