Those graphs are deceptive because they zoom in; they essentially make the Wii review average the baseline. Zoom it out to start at zero and everyone will say 'so what? there's no big difference.' Throw in the fact that the author is basically ignoring the standard of deviation, and you have a bunch of really deceptive graphs. The author does make interesting points, but trying to justify it and fool people with these graphs is kind of low.
IMO the big problem with Wii games right now is that developers are throwing in motion controls even when it doesn't make sense. They feel like they have to because its the selling point of the Wii. They haven't yet realized that simply shaking a Wiimote is not a game. A lot of them are simply cashing in; they know the Wii is 'in' right now and are trying to sell things to uninformed consumers. This usually happens later in a console's life, when it has established a larger user base, but the Wii seems to have struck a chord.