Direct graphics comparisons are not a proper indicator of hardware prowess. The PS3 is considerably stronger* than the 360 and yet many games look better on the 360. Besides that, your..."evidence" is still lacking as you fail to properly associate which technical aspects (textures, shading, lighting, FOV, etc) the Wii U has over its competitors. It's especially strange that you didn't take into account the substantial amount of time developers gained to make the Wii U version look better.
Putting all that asides, the Wii U is very close to PS3/360 and arguing about such a trivial amount of graphical difference is pointless. What's most important is how console exclusives will look. When the Wii U brings out a game that matches the visual fidelity of The Last of Us or Halo 4, that's when things will get really interesting.
*When I say stronger I'm referring to the eight core CPU the PS3 has over the triple core CPU the 360 has. I should note however that the 360 has a better GPU. Overall the PS3 is still stronger, but harder to code for since traditional game design places more emphasis on GPUs. This is why many PS3 exclusives (Uncharted 3, Heavy Rain, The Last of Us, God of War, etc.) look better and run smoother than most 360 exclusives and most multiplatforms (especially games on PC with DirectX) look better on 360.
