1,an actual leveling system where your guy actually gets stronger and tougher.
 I like monster hunter alot, but its broken if you want to actually do any damage to the big monsters you need to be a great or long sword. Which sucks because I love the bow and arrow, but in the demo in the whole hour of the first quest they let you do I must of shot over 500 full strength arrows at the monster and he didn't even flinch.
so if they put in a leveling system you can use whatever you want even the sword and shield and take down even the biggest monster in ther game if you were high enough level and would make playing it by yourself amazingly better

2, life-bars on the monsters
like I said I hit the guy with 500 arrows I'd like to know if I even doing any damage at all.

3 actual on-line co-op
if you need a hunting party to go take down most of the bigger monsters than why the fucking hell would not put in on-line co-op?