Monster Hunter and Final Fantasy XIV are too completely seperate games. and both require a different set amount of funds to create a proper version. Let's be honest here MHFO doesn't have graphics of un-believeable level. It wouldn't cost outrageous amounts of cash to make the game for the 360. Now XIV on the other hand does have ground breaking graphics for the MMO genre. It WOULD cost tons to make a 360 version. So Square doesn't want to invest that amount of money only to have it come back and bite them.
We will never know that exact amount of figures when it comes to dev costs. But just look at any XIV vid. You would know it would cost wayyyyyy more to develop.
Kudos to Capcom though for making XBL work for them.
FFXIV 360 will come in time. Just be patient.