How much heat does it generate?
More or less than the 65W of Power 7 (OoE 8 core, 32 threads, 2,4Ghz lots of edram a monster for any console standards)
or
20W (OoE 4 core, 16 thread 1,4Ghz lots of edram, still more gigaflops than Xenon, if you want to use that metric, still quite good the purpose)
You're comparing server chips with HUGE margins that can sustain shitty yields AND be binned for different profiles to a single-use chip that needs high yields and absolutely, positively has to be as cheap as possible.
It is not a reasonable comparison.
Also, 20W for the CPU alone would be far more than the cooling solution in the Wii has to deal with, and would probably be closer to the total heat output from the Wii U's CPU and GPU combined.