I waited to get the Wii until Mario Kart Wii was released and that's what I'm waiting for once again before I buy a Wii U.

It needs games, and exclusive ones. More IP's from Nintendo in collaboration with 3rds.

Also, apps. Cool apps. LOTS of freemium stuff to download and boot straight from your gamepad.

Multiplats are nice but if everyone has the multiplats, whats the deciding factor that prompts one to buy a product ? Something not available everywhere else.

Wii Sports sequel. 2D Mario that pushes boundraries.

I'm also going to be crazy and say Wii Music sequel that has a motion + drum set simulator and music editor and actual challenge and actual content and PvP.

Cool apps will give it novelty. The WiiU pad should be doing everything fun that an ipad can do, and then on top of that play full-fledged console games. Use the camera, use the touch, use the gyro, make cools apps that kids will see and want. That your girlfriend will see and want to try. Apps, apps and more apps. And MarioKart and GTA. Boom, lots of sales.

The last time we've seen more than one 2D Mario on a single console was on the NES I think, so -> Not going to happen. 

Maybe if you want the Wii U to do Saturn numbers.....

Ipad and iphones shipped over 70 million units last quarter alone.  At this point Nintendo would probably be ecstatic to sell that many Wii U's in its lifetime.  With that massive install base gulf, how does Nintendo expect to get developers to work on exclusive Wii U apps?  Apps are kind of past their novelty stage for most people, and even if the Wii U manages to have some exclusive ones that perk the public's interest, spending $300/350 just for an app that will inevitably be on other platforms (whether as a port or a clone) seems unlikely.

Not to mention, the majority of people who have or will buy a Wii U likely already own a tablet or smartphone.  Why would apps convince people to spend hundreds of dollars on a machine you can't even use outside the house.

They still need it though :P

It might not pushing boundaries, but from what I saw, it seems like the best Mario in the 'New' series. Looks uber-fun:

Why it does not sell WiiUs like it should? The game is bad? Not enough marketing? Or the price is too steep? What's wrong with this game specifically?

The mushroom kingdom isn't expanding anymore, and that will cause people to get tired of it. The music in insanely stale as well. For a game of this caliber, it needs great producton values and new content. Imagine if every new 3D Mario used a remixed Super Mario 64 soundtrack (no orchestra) and the same story and worlds (although remixed) as Super Mario 64.