Wii Music was an attempt to make something that had never been made before. The concept is WAY more "out there" than Brain Age, Nintendogs, Wii Sports or Wii Fit.
In addition to the problem of accessability, and the need to invest a lot of time to get a lot out of the game, there's also the issue of getting people to understand the concept without playing the game.
And so the game has had a rocky start, no doubt.
But where I lose you is the idea of "what it'll cost Wii."
Wii is loaded with long-legged mega-hits. Mario Kart Wii and Wii Fit are far from "old news." Their sales momentum is so massive it appears both have probably reached less than 50% of their potential sales. And Wii's holiday lineup has another mega-game, Animal Crossing, which is a much surer bet than Wii Music ever was, and which could be especially potent in Japan.
And don't expect Nintendo to take the foot off the gas next year. With the Play on Wii series, and all those games they announced at their fall conference, and Wii Sports Resort, Nintendo are doing plenty to maintain the momentum even if Wii Music totally flops.
"[Our former customers] are unable to find software which they WANT to play."
"The way to solve this problem lies in how to communicate what kind of games [they CAN play]."
Satoru Iwata, Nintendo President. Only slightly paraphrased.
