I'd be thrilled if we got rid of the arcade terrains and used something more realistic in the MA's.
There's something about a gigantic mountain erupting out of the ground at an 85 degree angle and soaring to 20,000 feet... it just doesnt do it for me.
Careful what you wish for. The extreme mountains, in most cases are to create bottle necks by design.
If the terrain was realistic, there would be 12 hour missions. A lot of what is done, I believe, is to pack more fun into the game. HTC does an excellent job in this regard.