FaRmLaNd on 08 December 2008
Several reasons.
1: The game has a broader appeal, which is shown in its marketing
2: The wii has a far larger install base
3: It was marketed more heavily overall
4: It has wii in its title
5: The wii is being purchased a lot more then the ps3 and wii music would be a natural choice for many new wii owners as its new itself.
