Power isn't just graphics. For instance bioware tweeted they couldn't put a holster animation in ME3, because the PS3 lacked enough memory (idk if I buy this but it's what they tweeted!).

also, while gameplay is great... gameplay with great graphics is even better. Artstyle that's great is even better if the graphics are great from a technical perspective too.

If it has worse graphics it needs to have some things that offset it. For instance wii games were cheaper. The controls (though I think this was a negative). The console was cheaper. If the wii-u doesn't have those things, that seems like quite a negative to me.

If all things are equal, having worse graphics and processing power is definetly a ding against it, and I don't know how you can argue otherwise. The idea that games on nintendo consoles are the only consoles with games that have good artstyle or good gameplay is kind of stupid. And they've generally had the worst online as well. And though developers don't take advantage of this a lot, there are gameplay possibilities that only happen with higher processing power.

With all that said, who knows what's going to be the wii-u. It's rumors. 

I don't think the problem with Wii U is the graphics (although it will make it a harder sell to 'core' gamers) I think it's the fact that the touchscreen on what is otherwise a return to a traditional controller is no where near innovative enough to win over people and compared to Wii, Kinect and Move seems like a step backwards.

However, it'll be the software not that hardware that ultimately wins the day. Wii would not have been the hit it was without Wii Sports and Wii Fit. However, so far we've seen nothing of the (potential sales) calibur of Wii Sports or Wii Fit for Wii U. Nintendo better have something genius in the software department or it'll lose to Xbox Durango with it's much refined Kinect gameplay (assuming MS comes up with innovative gameplay to sell it).