@OkeyDokey
How I tire of such misinformed statements. Check out the music videos thread, or perhaps actually try the game, which is superb, before showing your stupidity. Also, if you are basing your statement only on the data above, notice that its numbers are very close to those for World of Goo, which is generally heralded as a tremendous success of game design.
I, for one, wish I had more chances to play Wii Music, but it takes a good investment, at least a couple of hours, in order to come up with and execute a truly clever arrangement, 2 focused hours alone that I don't often have; plus, it is not a very good social game unless you have very musically inclined friends (ie. not merely those that would enjoy following along with Rock Band, but those that would enjoy playing with musical ideas and styles). Time data will always be misleading, and it will trend towards either (A) demographic groups that have a tremendous amount of free time (younger "hardcore" gamers), or (B) party games that you can pull out in any social setting and enjoy. A clever game that is decidedly neither targeted at the young "gamer" crowd nor party-friendly will inevitably show misleadingly mediocre time data.