In TN we have very liberal doe limits and for the most part I think your hunters that hunt all seasons (bow, muzzleloader, and gun) will let the smaller bucks walk and take a doe if their looking for meat or doe reduction of their herd.
Now during gun season (in my unit) we have a zero doe rule unless: your a landowner, sportsmen license holder, or you buy a special permit (type 94). So what happens is your "weekend warrior, i only hunt with gun" hunter will shoot the first deer that walks by him because they do not hunt the other seasons when they could have taken up to 3 doe a day. They dont buy the permit because they dont want to waste the extra $$$.
Thats just my 2 cents. In TN it has gotten better on QDMA in the past couple years. Last year was the least amount of yearling bucks taken in the past 20 years.
My other thought is along with Bruce's. Hunters being green to the QDMA process. I know and like an older guy that owns several hundred acres. Up until last year he would not allow anyone to shoot a doe on his land. He claimed more does equaled more bucks. So the more bucks you would see. You also have alot of old school thinking still around of "If its brown its down."
Im like ronn on the "Its your hunt, do what you want with it." Even though I will sit and watch a spike or 4 point all day long it doesnt bother me if someone takes it. Thats just not what I want to shoot anymore. Now granted if im going hungry that spike better watch out. I got a 2nd cousin that will take any deer he sees, it doesnt matter what size it is.