I'd like to see a couple things. I don't see how MOUT would be applicable in this situation, this is going to be vietnam you know. I suspect most of the fighting will be in jungles. But I can see how MOUT would be very useful.
Anyway, I'd like to see a few things...
1) Change the AI targeting system. Right now it's set up so the enemy will shoot at you when they can't see you. Usually another AI, the officer perhaps, can see you, so they'll tell that soldier to shoot you. He sees a yellow box, shoots at the yellow box, and if you're prone and crawling like you should be, he'll hit you. The problem is that he will often hit you through bushes and leaves so you can't see him, but he can still somehow hit you. Anyway, this is a very big downside that has ruined many a mission in OFP for me to the point where I had to fight the enemy in the open to get the job done.
2) Clipping. In OFP now the clipping is horrible. My player gets the shakes when he gets too close to a wall. Enemys can shoot through walls. Players are constantly falling through walls. Clipping is what makes MOUT so horrible. I think if the designers fixed this clipping problem as well as the AI targetting system MOUT would be much better.
This is just the beginning of my laundry list. I think most of these things will be fixed since OFP2 is coming out in a new engine anyway.