The CPU in Wii U is based on the 'Broadway' CPU in the Wii which was based on the 'Gekko' Gamecube CPU, three cores/threads clocked at 1.24GHz with a bit more cache than the Wii which has a theoretical peak of 15GFLOPs
I'm not saying whether you're wrong or right, but has there ever been a decent source for that claim? Or are we still quoting one post from some random guy on twitter as a hard fact?
The 360 CPU has three cores with SMT which means 6 threads clocked at 3.2GHz which has a theoretical peak of 100GFLOPs
The PS3 CPU has two cores with SMT which means 4 threads clocked at 3.2GHz but also has 8 SPEs which generate 26GFLOPs each, it has a theoretical peak of 230GFLOPs
You can't directly compare the power but for arguments sake we will and as we've seen GFLOPs aren't everything, the PS3 CPU on paper is twice as fast as 360 CPU, but in reality its a complicated bit of hardware to optimise and code for. But even when you take that into account the Wii U CPU is FAR weaker than consoles that are 6+ years old. It does have a saving grace of a far newer GPU rumoured to be based on AMD 4770.
I think Nintendo have made a big mistake basing the CPU on the same/similar architecture as its previous underpowered consoles for the sake of backwards compatibility, it could have had a for more powerful CPU and this discussion would have been moot.
It's no surprise companies don't want to put the resources into porting their engines considering the lack of power and relatively weak sales.