Wii's downstream market is near complete saturation.

[johnsobas]

for one thing releasing a sequel too early on wii is stupid because the legs are so long that many of them aren't done selling when the sequel comes out.
Some of those examples are not fair at all, it took boogie a really really long time of steady sales to get those numbers, same with bloom blox. Both bloom blox and boogie were called bombs when they came out by many people, and ended up being pretty big successes.

There is a point to make that sequels haven't always performed well for some games, the best example is probably trauma center. Some games are the type of games you only want to buy once.