More on the topic:
Crappy games also have a ripple effect. If someone plays a game or two on a specific console, they might associate the bad gaming experience to the console as opposed to the game itself. They will then tell their friends about it, and they in turn will be less likely to purchase the console. I can see this happening more typically to the casual gamer, who isn't likely to take the time to actually research a game or console on their own.
The Wii does have the advantage of motion control, so it's not a typical console, and can sell on that feature alone - which it seems to be doing.