We had super smash bros. for both 3ds and wii u, yet we don't have Super Mario Maker for 3ds. I mean really, I get how Nintendo is trying to create some sort of console exclusivity, but it's not going to go very well for your 3ds fanbase if you're only going to release the high demand games on wii u because once you leave 3ds users in the dust, more people are going to buy the wii u, and then the 3ds won't sell well anymore because more people are buying the wii u solely for its game library. Then once they try to release a popular 3ds exclusive game, new and old wii u users are going to be screaming about how it's only on 3ds, just like we are about a portable port (which I do agree with you on how much of a great idea that is). Plus, it's Mario's 30th anniversary, so why not put it on all modern nintendo consoles, as well as form a more similar game library among popular games on both 3ds and wii u?
Oh and by the way, the fact that the wii u won't sell very well in the end is nintendo's fault (no offense to wii u lovers).