The Wii's GPU did indeed have a fixed function pipeline, but that fixed function pipeline did support normal mapping. ("dot3 bump mapping" as was the style at t

The Wii's GPU did indeed have a fixed function pipeline, but that fixed function pipeline did support normal mapping. ("dot3 bump mapping" as was the style at the time.) However, the Wii's GPU only had 1MB of texture cache. So it was generally preferable to do more work with geometry than with textures. Some exec from Nintendo is on record as saying something along the lines that texture mapping looks bad and should be avoided. My conspiracy theory is that it was a conscious decision at Nintendo to limit the ability of its consoles to do stuff with textures. The N64 was even worse, a lot worse: it only had 4kB of texture cache.