If we re-visit the Wii launch too ... imagine if Nintendo didn't delay Zelda: TP and move it into the Wii launch window.
Sure with Wii Sports it would've done well with casuals, but that means there wouldn't have been really a big Nintendo "core" title until the following August with Metroid Prime 3 Corruption.
That would've been a *huuuuuuge* drought.
I mean yeah, Twilight Princess didn't help the Gamecube much, but really who cares? GameCube was what it was and Twilight Princess wasn't changing that. Much like I really don't think Zelda U is a game changer for the Wii U one way or another. To be honest an arguement probably can be made that Pokken Fighters i the more ideal holiday title because it can sell a lot more amiibo toys and toy sales are much tied to the holiday season.
Beyond that I'm not even that confident that Aonuma's team can even finish Zelda U for November 2015. It sounds to me like given open world nature of the game and it being the first true HD Zelda, that the dev time here is probably going to have to be longer than TP or Skyward Sword. Moving the game into 2016 probably gives the dev team breathing room to really flesh out the game fully in the way they want to.