Just some random thoughts on this. I started hunting in MT in 1977. On and around my grandparents ranch in Eastern MT and in Southwestern MT both public land and a friends ranch.
The number of deer and size of bucks has declined a great deal. In E. MT it was normal to see multiple mature bucks most every time out.
In W. MT the ranch and surrounding public land held lots of Mule Deer and there were mature bucks to be had. Elk were pretty scarce, and Whitetails were too. Now the Elk and Whitetails far outnumber the Muleys. There ranch itself, which goes from the base of the mountains to a river held only Muleys- no Whitetails. Now it is all Whitetails. Haven't seen a Muley there in 20 years. We went to tree stand archery hunting for Whitetails- you see hundreds of them.
In the Tobacco Roots they did institute a 4 point or better and closed it before the rut for a couple decades. This didn't increase deer numbers, but it did allow some pretty big 3 points to survive.
The FWP relies on public comment before changing anything ( don't know how or if that works). I talked with a FWP biologist about the problems with Mule Deer, and he said:
Whenever there is public comment the number one thing people overwhelmingly want is opportunity to shoot a Mule Deer (meat hunters)
He also said:
Part of the decline is due to many years of drought reducing winter forage- Muleys are not adaptable. If their normal food supply is diminished they die, they don't eat something else or move to a different area. This is why there is no transplant programs for Muleys. The state capital, Helena is overrun with them. They shoot them to reduce populations, because if they moved them they will not adapt.
Increased competition from elk and whitetails pushes them to the fringes of their preferred habitat.
And I do believe more predators and more subdivisions are also part of the equation.
Except for mature bucks Mule Deer are DUMB. You could have a 2 week season, and everybody that wants meat, will get one.
My son and I drew limited tags a few years ago, and it was a fantastic experience. We saw a lot of deer and a few mature bucks every time out. The area across the road is general tag, and you will see less than 10 deer there most days.
I don't know what the answers are. I don't think its ever coming back anywhere near what it was.