Considering the dominance that the platform you are comparing had in those years compared to the non-existant of the succesor, multiplatform releases is the only logical reason. I doubt publishers are loyal to a certain hardware producer and more like bussiness men, with horrible decisions sometimes.
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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