From a developer standpoint, generations are clearly defined as being able to use similar game assets and engines when porting a game from one system to another. Any console that lands outside of that construct is clearly in a different generation (because it costs a whole lot more money to support a console with radically different specs). As such, the WiiU isn't "next-gen", much like how the original Wii is far closer to the PS2 than the Xbox 360 and PS3.
The real side effect however is how development studios end up treating that console. We've seen this story before. The Dreamcast was not so clearly defined as being "next-gen" when it was released in 1998, and it was doomed to failure because 3rd parties didn't support it enough. I feel like the Wii U is destined to have a similar fate.
I think we all agree that Nintendo can really only pull the Wii "Blue Ocean" strategy once. 2012 is nothing like 2006. Nintendo is competing with far more than just Microsoft and Sony in home consoles, they have to deal with iPod Touches, iPads, iPhones, Nexus 7s, Kindle Fires, Android phones, Facebook games, you name it. Ultimately, a kid only has so many dollars to spend for Christmas or their birthday.