I believe that the Wii can have ok quality, i think the only problem is that the big companies like EA and what-not don't utilize the graphics that the wii has. Ps3 definitely has better graphics and online, but i think that video gaming companies don't take the wii seriously. Like it's only for young children, but adults buy wiis too.
Believe it or not, people aren't mobile ATMs :-0 . They probably would rather put money into a cheaper system that has decent graphics rather than put it into a $600 game system with $60 games.
Honestly, there isn't a damn thing that the Wii does better than the PS3. On top of that, it seems like every Wii XXXXXX game they release is the same thing as the last. Wii Sports - Yay, Wii Fit - Neat, Wii Play - ...seriously?, Wii Sports Resort - You've got to be kidding me.
Heck, even games that are made by third party companies all end up using the same gimmicky, inaccurate Wiimote motion sensor functions and boil down to the same thing.