I'd say the Wii gets hit harder in the reviews on average because of it's technology.
When you have a game on Wii and it doesn't use the Wii controls perfectly, big minus points.
You have a multiplat game for Wii, but since the graphics aren't as good they see it as an inferior game (with the exception of PES 08)
If the game has graphics that are only marginally better than the GC, they get docked.
That and pretty much the only company even attempting to do something with Wii is Nintendo themselves (and maybe Capcom to an extent). 4 out of the 5 90%+ games are made by Nintendo, with RE4 taking up the last spot.
I think most reviewers are a little biased towards the "next gen" Where pretty graphics can give a good game a better score (i'd say Gears of War was awesome and a 9/10 game, but i'm sure it's graphics brought it up to 9.4) Had Gears of War stayed exactly the same in every way but it's graphics level brought down to the Wii's capabilities, it would have never gotten out of the 8's.
If i wanted to dig deeper i could say that Wii and 360 have the same amount of exclusive 90%+ games, but that's just cherry picking. In my opinion these review averages are meaningless and show nothing of a consoles library. What should show a console being successful (sadly) is the amount of shovelware. Like PS2 Wii has tons of it, and thats not gonna change.







