User blog comment:Mckrongs/Monster Hunter Wiki: User Suggestions Board/@comment-24.255.21.21-20100917085220/@comment-158109-20100919151354

Probly cause everything is brand new. They had a fresh start on graphics, physics, better environments, the monsters are 10x smoother and realistic, there's SWIMMING and swimming monsters, etc. All these completely new features lowered the number of final monsters.

And besides, I'm sure they've made a crap load of monster models and now they're dumping em on MHF3.

MH3 had 25 monsters, MHF3 so far has 34 monsters, and there's still like 3 months to add more.