The problem with the Wii is they took the DS philosophy (innovative control scheme + less graphical/processing horsepower than competitors) and tried to make it work with a much more complex input device and a console that, while graphically inferior to the other current gen systems, still requires a fair bit of effort to get an adequate looking game out of it.

On the DS, it's possible for a small team to create a decent and original game without having wasted too much of the publisher's money if it fails - they're able to experiment with previously untested concepts, and that's what makes the thing great. On the other hand, if you apply a similar small team and small budget to the Wii, they may have a great idea but they don't have the time and resources to realise it fully, and you end up with something that looks and plays like a PS2 Simple2000 game with poorly implemented motion controls bolted on.