According to a well-argued piece by the New York Times, Wii owners don't buy games. They look at the issue from a variety of angles, including the facts (Wii owners buy one game less per year than their 360/PS3 counterparts), the analysts (Michael Pachter explains this represents a "broadening of the demographic") and the consequences (Super Smash Bros. Brawl sales dropped 90% over the first four weeks, forcing companies like Walmart to turn to bundling the game).
All in all, it's a good thing that Nintendo makes loads of cash on the Wii, Wii controllers and accessories for Wii controllers. Because even their traditional franchises are failing to inspire many of those who purchased Wiis in the first place.
New Wii Games Find a Big (but Stingy) Audience [NYT]