Capcom needs money. They are spreading their wings with MH.
Upcoming:
Monster Hunter Portable 2nd G (PSP)
Monster Hunter 3 (Wii)
Monster Hunter Frontier (PC... constantly updated)
They said themselves that it's too expensive to produce games on the PS3, but secretly you know the real reason. Capcom wants more PS3's to be in homes before they make the PS3 MH. It will happen, but only when they feel it's the right time. Remember Biohazard: Code Veronica for DreamCast?? Same exact situation. Big name title exclusive for DreamCast, but Capcom constantly held it back because they wanted more users available. So they release '3' on Wii to make buckets of money in japan. Good for Capcom, and in the end, good for the series. Great thing here is, '3' might actually be released in america..... Imagine that??