Theory

The Wii userbase is the most deceiving userbase in console history. The number of consoles sold doesn't reflect that the fact that half the userbase doesn't play video games.

Reasoning (Spiderman 3)

Spiderman 3 is a movie to video game. All gamers know that these games are usually crap, the only people who end up buying "movie" games are parents who want to please their kids or people who generally don't have a clue about video games (aka Wii target market).

So therefore you would think the Spiderman 3 sales for the Wii would be big or at least bigger then the PS3 or 360.  But as you can see below isn't just not the case. Something is wrong with the Wii userbase

2		Spiderman: The Movie 3	Activision	194,394	194,394
3		Spiderman: The Movie 3	Activision	142,597	142,597

5

Spiderman: The Movie 3

Activision

79,541

79,541

9

Spiderman: The Movie 3

Activision

39,741

39,741

Conclusion and Final Thoughts 

This could be simply to just to low sales, or the fact that 3rd party developpers just don't seem to sale on the Wii.

On the other side though this could be a sign that the Wii is just a fad, , it's something to own and just to show off to your friends and play a couple rounds of Wii Sports but never really to play video games.

Spiderman 3 (the movie) is the giant blockbuster of the summer, there's no reason for it to have such low sales for such a high userbase.  Unless of course the userbase is completly F*&#ed and half of them don't play videogames.

The Wii version is garbage. That's why it's not selling.

Could it instead be the following? 1. The game in question was reviewed extremely poorly across the board, so "hardcore" gamers who are up to date on these sorts of things stayed away 2. There are other games on the market that "hardcore" gamers can buy, for instance Super Paper Mario 3. A large number of Wii owners are casual, which you misdefined. Casual gamers buy one or two games a year, and they're still having a blast with Wii Sports

Could it be that Wii owners actually have a good taste and don't buy crappy games, unlike owners of the other consoles?

If it was a good game, you might have a point.  But the game sucks on all platforms, with the Wii arguably the worst.

So what you say may or may not be true, but this isn't the game to use as proof.

Because the Wii game is awful to play, and looks awful, whereas the other ones were only rubbish to play

Meh, i thought the same thing kinda, i knew sumfinw as up, especially considering that there are many wii owners. However, it has to be said, the Wii version is by far the worst

the wii game sucked now ppl arent that stupid 

I buy Nintendo consoles because of the quality of their 1st party games, for me as a company they havea body of work that no other video game company can get anywhere near, although I am not saying no other company can make games as good as Nintendo but no other company has the sheer number of quality games Nintendo have produced over the years. So to play Nintendo games I have to buy a Nintendo console, I don't even consider what 3rd parties may release before I buy my Nintendo console but it's very nice more and more companies are supporting Nintendo consoles but not important to me as all it seems to mean is more racing games, sports games and and endless number of FPS that to me play all the same.

Look at the screens and you will see why its not selling.

But i see your point in that the little kids who want spiderman and don't know anything about graphics would want it. So this could prove that the Wii userbase is a little more "hardcore" than you thought.