Didn't Tales!! come out around the same time as Baten Kaitos?
Also, I'm not sure if Manhunt is a fair test to determine the mature Wii market against; isn't it even a bit extreme for a lot of that market!?
For example, GTA is seen as a mature series, yet it gets bought and played by people of ALL ages. The same can't really be said about Manhunt, so sales may not necessarily reflect the market.