Nintendo's typical art style is cartoonish, which doesn't place very high requirements on the hardware. Zelda Wind Waker, which has been claimed to be native 1080P, does not run even close to 60fps, nor does it use a whole lot in the way of textures.
Wuu's main CPU is also very, very weak compared to even last generation of consoles (like 1/10th the flops of Cell or roughly on that order), the GPU is something akin to what you'll find in a budget laptop, and the system as a whole has very low main memory bandwidth (half of PS360 main RAM.) So it's not a powerful design by any stretch, even when eDRAM is taken into account.