It would be a bad thing for Nintendo to have Wii U graphics in the middle of 2 generations. Knowing Wii U won't be a next next-gen, I have zero doubt its power will be close to a x360. That way it can enhance the incentive for devs to keep developping games for the current next-gen: the userbase will remain big enough to be attractive, moreso when you factor increasingly powerful smartphones and tablets.
Nintendo also has to create assets for its next handheld, which could approach x360 level in few years.
Besides Nintendo games will look great with this tech, even the most simplistic ones, because of their artstyle.
At last Nintendo expects people to use the GamePad to play games with the TV off. The closest thing that can offer a current next-gen experience on a mobile device is the Vita, and Wii U is significantly more powerful than it.
It makes sense if you are Nintendo to release a console with the tech it has.
Not necessarily;
Let's quickly consider what Nintendo can gain from a
relatively (to ps4/720) weaker console yet built with a similar architecture
Iwatas quotes to investors, to me, seem to be more than well aware of the issues that plagued the Wii and why it didn't receive all the big games they were hoping it would get
So what was the main reason? It was not cost effective to port. If a game was made ground up for 360, it was simply not worth it to port. Some companies like EA had GameCube engines which they could simple transfer to the Wii, so they made many multi platform ports for their large franchises (sports, nfs, etc) but with everything else it didn't seem to make sense and according to many publishers the return on cost was not worth the effort
So with the Wii U, Nintendo set out to change this. First, it's a next gen system. Nintendo isn't stupid, they know the 360 and PS3 are dying consoles. So they looked towards industry trends. Are people really so naive as to assume they didn't consult with IBM and AMD as to what their architectures would look like around the target release date of wii u? That is something that boggles my mind but also explains how some people can believe they have millionaire dead relatives who were princes in Nigeria.
Ok, anyways,
They realised it needs certain features to run certain engines. So they can go to amd, an request a card that will cost them X amount of dollars yet has X and Y capabilities so that when the next systems from competetors are released, they will not be in the same position as they were with Wii
Thus, the architecture is designed in accordance with "modern" standards.
It's more important if a system has the capability to run something than the horsepower. Think of engines as gasoline for cars. The wii u is a new "hybrid" vehicle unlike the 360/ps3 has guzzling muscle cars.
The 720 and ps4 will be like super sporty hybrids.
They are all still hybrids. They utilise fuel differently, and new fuels need to be created an crafter for their new designs.
This hasn't happened yet because most car owners still have gas guzzlers, not hybrids
So the hybrid engine of the wii u won't be fully appreciated until hybrids become more common
It's not as fast or powerful as the other hybrid sports cars (ps4/720) but its not a Prius or something either...it's still a powerful fast car on its own
Does this make sense?
By making the parts more cost effective, Nintendo can sell it to a larger population without losing money themselves.
It's a balance, an I think they are looking for balance between raw power, affordability for consumer, and profit margin for themselves