Nintendo, like many companies, does market research. If they didn’t, that would be pretty stupid. Recently, the company conducted some research into the popularity of their Wii console in the United States and Japan (because Europe and Australia just don’t count, I guess) and the results are pretty interesting:
In both regions, children like the Wii. However, as these children reach their teenage years, they drop off. In Japan though, more people around the age of 35 pick up the Wii, whereas in America, the userbase is predominantly children and teenagers (although there is a slight increase in that age range, it is nowhere near as big as Japan’s).
Satoru Iwata also mentioned previous research that shown that adults tend to find Mario childish and he claims that he hopes Capcom’s Monster Hunter Tri G will fill this gap, although he believes that the absence of the game overseas will not have a drastic impact on that market.