It's just so interesting how a lot of these markets have split. That despite Wii dominating in the hardware and usually software it has been unlike the PS2 in dominating the software front in similar ways to the PS2 but no doubt still sells a lot of software. Why? Well I think the best theory would be that Wii has not necessarily closed the PS3 or 360's main appeal market down, that being the hobbyist gamer. Wii has appeal there but 360 and PS3 are specific to that appeal thus they are going to get that as their majority of software being bought. While Wii still gets that it doesn't get as much because its kinda at a split with its multiple appeals.
So it allows the PS3 and 360 to really survive software wise in a lot o these markets such as the UK. Would be a lot worse for PS3 and 360 were on par to the Xbox and GC last year where they were unable to really grasp a stronghold into the core market.
People are always wondering why Wii versions of the games don't sell as well or why those 2 with smaller userbases can still sell. Well that is the most likely answer being that while Wii has split appeal on those core games Ps3 and 360 have direct appeal to them. Not to mention its more than likely multiple consoles are owned between those hobbyist that would choose the 360 or Ps3 version over the Wii. It's this thing that we criticize Wii on for not dominating fully that actually allows your PS3's and 360's to continue to have a market haha. Oh how things work.
