Monster Hunter is a handheld franchise and Capcom has shown to be unwilling to work on a HD level MH game (Monster Hunter PS3 was announced before PS3's launch, but cancelled later on in favor of the much more successful handheld titles). They'd rather squeeze as much out of the IP as possible, so much like Pokemon games still look worse than PS1 games, the games won't advance past their PS2-level graphics for a while still, not until they absolutely have to (because that would mean more money to development and thus less profits).
While I agree mh is a handheld series at this point Sony could have ported monster hunter online.
Would be a smart move for Microsoft to make. There's a lot of korean/chinese pc content that could be ported to these consoles that might be of interest in the Japanese market.