PS2 had all the casuals but they were teenagers that were mainly interested in games like GTA, GT etc.
Wii has all the casuals and they are only interested in fitness games or first party nintendo games. It doesn't matter if you make mario clones that are better then the mario games it will never sell as well, so why bother;p?
Wii gives a different experience then the HD consoles, it is a good and fun experience but if you want the HD ones buy a xbox/ps3.