Yes, because it will be a better Zelda game on the Wii U if it also comes out on the NX. If Zelda U is a Wii U exclusive then it will go like this: Zelda U will be released as an extremely late-gen title and is likely to be out right in the middle of the NX's big marketing push. The game will come out and will quickly be pushed under the rug because Nintendo wants fans to be focusing on the new console. Zelda U will be treated like the fullfilment of a commitment by Nintendo to its fans and Nintendo (knowing this) will likely have produced a good game but not one that will be revolutionary or that will take too much attention away from the NX.
If, on the other hand, if Zelda U comes to both the Wii U and the NX then Nintendo will be able to justify devoting far more resources to the game's development. It will be a launch title that is designed to take the gaming world by storm (the same way that Mario 64 did) and Wii U owners will be the beneficiary of this since they will get a game (albeit with slightly reduced visuals) that punches way above its class had it been released as a late gen Wii U exclusive.
I think Zelda U coming to both platforms will be good for both Wii U and NX gamers as we will get a game that was truly crafted to be the best it could possibly be. Wii U gamers like me just need to be able to swallow our pride and accept that Zelda U won't be our exclusive treat anymore... The definitive version will likely be on the NX but we will still get an amazing game!
