I don't have a good answer. I am blessed to be living at a time when it is within my means to seek adventure and yet uncomfortable enough that most don't attempt it.@JaSAn , well I suspect that why you saw way too many bears there are many more people in YNOP but the bears are more scattered now, due to using natural sources for food.
I think it was in the '70s when they started shipping problem bears out, attempting to educate the public and fining those caught.
And yes, we have expanded refuges/etc, they however, at least in part, don't get as many people because of a multitude of issues.
I don't go to most refuges near me due to hunting being allowed on them and the wildlife being scared of humans. (This isn't saying "hunting bad", it's just pointing out that wildlife behaves differently due to such).
I would recommend you try some. I saw way more elk in the Charles M Russell National Wildlife Refuge in Montana than I have ever seen in Yellowstone, and that includes the winter. I even had a small herd wander through my camp with a beagle going nuts in the camper.
I say expand more. Science has been pushing that to just keep current level of biodiversity, we need much more land protected from development, we need to fight fragmentation of habitat.
The problem is that the amount of wild land is fixed and the demand for use said lands keep expanding: hunting, fishing, timber, mining, oil & gas, ATVs, snowmobiles, et.al. Not to mention overlanding and dispersed camping so important to this crowd.
Also, it wouldn't be a bad idea to tackle the most significant issue, human population. As long as more people want to go "out" into diminishing space, well, ya know...
I see the problem differently: people in this country have more disposable wealth, so more can afford to visit 'nature' without forgoing the comforts of home. Combine that with facebook, instagram, twitter, et.al. and natural wonders are getting a lot more press than they used to. So more people can visit without inconveniencing themselves too much.
Maybe the answer is to go the direction that my beloved BWCAW went and restrict the number of visitors to wild places to minimize impact. I like keeping wild places wild but IMO our National Parks are very far from my definition of wild.