Who do you propose should own it? Highest bidder? We don't want/need another generation of land barons out here.
Right now I have the right to use the land (and do routinely) along with the rancher's cows. He can't keep me off that land - but he would, almost without exception, if he could. That's because a small proportion of the public who uses the land he leases doesn't behave when they use it and it costs him money sometimes to clean up or fix their messes. I say his grazing fees are so low that he should be happy anyway and that that's the cost of doing business.
The thinking is that the current use patterns, private grazing and mineral extraction, public recreation is the best use of the land. In other words it brings the most benefit to the most people of the available uses.
I think this probably deserves it's own thread, it's an important discussion, but there probably aren't enough westerners, familiar with a landscape that includes a preponderance of public land, here at ES to make it a thorough discussion.