Easy answer - they are public lands, belonging to the entire citizenry of the United States.
The BLM is essentially subsidizing the ranchers' operations, while denying the public use of public lands.
Given that "natural areas" (like national parks) are tiny little disconnected tracts of land, it makes a lot of sense to rehabilitate public land and re-naturalize it, for the benefit of everyone.
For several species, their long term success depends on free movement over larger areas. Restoration of ecosystems and undoing a small amount of the massive environmental destruction of the past couple of centuries is a worthy thing in the eyes of most.
That's why, for example, dams are being decommissioned and rivers allowed to flow freely, to re-establish natural environments for fish and many other species.
Honestly, why do some folks think that every square inch needs to be plowed, grazed, drilled, drained or paved?
Well, as far as that area of the US is concerned, the wolf they introduced is not the wolf that was native to that area, and personally I fail to see how killing "every damn last elk" is "restoring the natural balance". Maybe you can explain that one?
Fact is, no one knows what the "natural balance" was in that area, or any other for that matter.
As for the "people of the United States", has anyone asked them? As if!
I'm all in favour of helping and preserving the environment as much as possible, I do as much as I can, but it's not my religion.
Yes, national parks are going to remain disconnected, unless you'd like to give up say 80% of your property so that all the people displaced by their "reconnection" can live somewhere else? What's next, tear down the fences and get the bison herds roaming the prairie again? I hear all the rhetoric of the radical environmentalist. They usually live in nice, big houses I've noticed.
Who thinks "every inch needs to be plowed..."? Why do some folks always throw up black & white arguments as strawmen to stifle serious and informed debate? Typical propaganda.