Vick,
Helicopters don't need MOA airspace to operate, as I'm sure you know. So that argument is specious.
I was told repeatedly by senior (as in O-6) AF airspace personnel that AF aviators currently operate under a 500 agl low altitude limitation, with a very few individual aviators who are permitted to operate as low as 300 agl. I was also told by many AF aviators that they simply do not operate down low in a combat scenario. It sure is fun to play down there, though.
I'm a firm supporter of our military's ability to train, and I do respect the folks out on the pointy end of the stick.
I was heavily involved in the establishment of the Eastern Alaska MOA Complex, which was a multi year process. During that process I spent a lot of hours with all levels of AF and Army aviation as a representative of civil aviation.
The AF in that case did compromise to some degree, even though they wound up with the largest block of training airspace in the country. Now, they (AF Airspace types) are trying to "clean up" some of those little "mistakes", which, by the way, were important concessions to civil aviators.
In many discussions with Air Force aviators, I repeatedly asked them when the last time that US tactical air forces operated at low level IN COMBAT. Every one of them said "Viet Nam".
The argument in the Eastern Alaska MOA complex, for having that airspace low (as in down to 100 feet) was that "we have to be able to train with our partners" --as in the British. Are the Brits training in WY?
But, gotta be prepared, just in case someone wants to reduce the fighter pilot forces real quick by execution

.
And as I noted, the Brits became famous in Desert Storm by getting Tornados shot down while operating low level. More than one.
As I said, I have great respect for the aviators operating. I also have great respect for the civilians who have to function around these bits of airspace. In many cases, the MOA airspace creates havoc.
Show me a valid documented situation where US operated high speed aircraft ingressed to a target area at 500 feet in the last 30 years, and I'll shut up on this.
Also, I think to cite "Theater Restrictions" as an excuse is also a bit specious, cause there have been and will be theater restrictions, at least in part to keep people from getting shot down. Certainly there are other political reasons for theater restrictions, but nevertheless, these are operational realities that apply to ALL areas of operation.
I've operated in and around military airspace a lot. I've seen a lot of good behaviour by military pilots and some very bad. I don't mean to suggest that the bad apples represent the whole program at all.
My point is that, having asked this question MANY times to military aviators at all levels, NOT ONE of them has ever given me a valid reason why they need to operate low level.
And, by the way, since the Eastern AK MOA EIS program, I've gotten to know a few of the senior fighter pilots who were involved on the AF side in that. Those guys have told me on several occasions that they felt the AF asked for and got way more airspace than they needed to train. They are now retired, by the way.
MTV