Maybe the graphics are too much for the Wii U to handle? Then again...
http://www.nintendoworldreport.com/news/35346
When asked whether Minecraft, developed by Mojang, would come to Nintendo systems, Nintendo's business development manager, Dan Adelman, said "What can we say on that front? [laughs]."
Nintendo has a "continuing relationship with Mojang" according to senior manager of marketing for licensing, Damon Baker, despite the lack of Minecraft on Nintendo systems. He went on to say that one of the reasons Nintendo goes to events like the recent PAX Prime, is so they can see what games companies are making for other platforms.
Previously Mojang has said it was "very unlikely" that Minecraft would come to a Nintendo system. Minecraft is available on PC and Xbox 360, and is coming to the PS3, PS4, and PS Vita.