Free: Contests & Raffles.
I've hunted in there over the past few years, and there are a ton of hunters in there. Maybe their goal is to regulate the # of people so they don't have to worry about so many Yahoos running the wheels off their rigs looking for a spike to shot off the side of the road. If you're putting out money for a permit, and you know they're won't be many guys in there then Maybe people will pass up a spike cause they think they have a better chance of getting a bigger deer. I've seen some tiny ass barely legal spikes come out of there, and personally, I'd rather get skunked than shoot a tiny buck just to say I got one.
My guess is that it is a purely financial decision. It costs a lot of money every year to maintain roads and such, not to mention having to haul garbage out constantly. Maybe they are tired of providing a playground for so many people. I know that most hunter's are good stewards of the lands but not everyone is. With so many vehicles running up and down the roads, it gets expensive, not to mention liabilities for the company. Just my thoughts.