Pixel Perfect Productions has an article up that lists 6 things from each console that just downright sucks. You can read one Wii reason below, but click over to read all the rest.
1. It’s Underpowered
The Nintendo Wii is about as powerful as a first-generation Xbox. It is essentially a souped-up GameCube, and it shows. The graphics are sub-par and a large number of the games suffer from slowdown issues and the like. I’m sure second and third generation Wii games will look better than first gen games, but that’ll be because more games will be designed for the Wii specifically instead of being ports of old PS2 games.