The problem with this line of thinking is you have to realize that what reviewers are looking at as quality is not the same as what Wii owners are looking at as quality.
For example, if a game has clean, cute, simple graphics (Wii titles) reviewers will dock points for presentation. If there's no online reviewers will dock points. If there's no story. Etc.
Wii owners care first and foremost about fun, playing with others, lifestyle games (which reviewers have no clue how to review), and value.
Now value is interesting let's look at that. To an average Wii owner Mario Kart with it's simple graphics and gameplay is fantastic value because they'll play the hell out of it for months and months. Not only that so will their kids and they'll play it with friends and family who come over. God of War is horrible value to them because it's over in 6-8 hours with virtually no replayability. To them Mario Kart is a much, much better game.
My point here is it's a misnomer to say quality doesn't matter. It does. Wii owners tend to rely more on word of mouth and what they played at their friends. If their friend hates the game, they are certainly never going to buy it. Quality absolutely matters.
Game reviewers are just out of sync with the majority of people's values. They are stuck catering to a sub-set of gamers and scoring it only on that sub-set's sense of value. They are not scoring it on what matters to the majority of game players. And the internet and forums like this is a small vocal subset of the subset that game reviewers cater too. Don't use that as any kind of judgement of what gamers in general want.
Call of Duty, Grand Theft Auto, Gran Turismo and Halo are great games with cross appeal - They score well with reviewers and have great value to the masses because any of those will be played endlessly. And they all sell huge amounts because of it.
But Nintendogs, Brain Age, Wii Fit, Mario Kart, also provided limitless enjoyment and enjoy great sales. They also are all quality, well made titles. But they won't score as well because they don't cater to Game reviewers sensibilities.
For Wii reviews I put more faith in Amazon.com reviews than game site reviews. My main concern is: is it fun? Is it good value? Is it well made? I'm not so concerned about story, graphics, etc. which often reduce those games scores on game sites. And very often, game sites haven't even reviewed Wii games. Most Wii games in fact are never reviewed.
Conversely, HD enthusiast gamers put tremendous faith in game reviews and mediocore reviews can spell disaster. A FPS that scores in the 80's will be crushed in todays market because there's CoD (and others) scoring in the 90's to get instead. So neither those that pay attention to game sites nor those that don't and see what their friend has will get those games (because their friend didn't buy it for them to try it).