I've got two reasons here, I'll list them out:
 |
Monster Hunter Freedom 2nd G |  |
Capcom | 2.71m | ||||
 |
Monster Hunter Freedom 2 | |
Capcom | 2.30m |
I didn't know anything about Monster Hunter before this site, and these sales tell me it's huge in Japan. I'm interested.
A core 3rd party Wii game with great graphics and online play? I'm interested.
The series has never been big until it hit the PSP, and now that the next iteration is on the Wii, how would people not care? It's one of the few major franchises coming to the Wii, and it's seeing its first console release since it got big. People here generally hype the home console games more than the handhelds.
@DMJ: Stop crying! 
It takes a few iterations for many franchises to get their big break. Few cared about CoD until #4. Same with FF until #7. GTA3. Dynasty Warriors 3. DQ9/10 (hopefully!). etc.
