The problem is simply too many people, too little wilderness. Unless we stop growing and put some wild lands off limits (as wilderness), in a few short years there will be nothing left.
National Parks are overcrowded, but they are a tiny, tiny part of all the public lands. Your complaint is that there are too few places with nice paved roads and visitor centers and such for people to go, not that there is too little wilderness.
"in a few short years there will be nothing left" is so comically wrong it's ridiculous. You're looking at literally the top 5-10 most popular outdoor areas to go, of course they're crowded.
Even within national parks, as soon as you go more than 1-2 miles away from a road, you'll see very, very few people.
I've lived someplace embroiled in controversy over pursuing national park status. Most the residents are vehemently against it because it would trash the place and overwhelm it with tourist traffic and all the problems that brings. The supporters consist a small contingent of profiteering area land owners that don't even spend any significant time living there. They couldn't care less about what impact becoming a national park would have on the environment or the area residents' quality of life. They just saw dollars.
National parks are a double-edged sword. They bring often much-needed tourism dollars to typicaly economically distressed remote regions. But they do not improve the environment. They stimulate travel (often by air), pollute the park area, and damage the natural habitats.
If the goal is to preserve and protect, the last thing you do is classify a place as a national park and make it easily accessed and comfortable with infrastructure. You leave the place lacking roads, running water, campgrounds, and toilets, and certainly don't advertise it as a nationally-recognized place of beauty.
National parks are more about stimulating the economy than preserving nature, at least as implemented today.
Edit: spelling/grammer/I'm on mobile now.
Let me share a case I am familiar with. One of my favorite short walks in my grandparents' town used to be one where you had to walk ~2km through fields, then a steep ascend of ~4km on a difficult rocky trail, then another ~2km through a nice pine forest to finally reach a beautiful lookout.
Then someone somewhere decided that it was a good idea to build a paved road so people didn't have to walk the first 6km.
To the benefit of who? Certainly not the environment: the construction of the road, polluting cars, garbage, soil erosion at the sides of the road from cars parking there...
It didn't provide any benefit for the people that walked there. Now you can hear cars going up and down while you walk. Some places are littered with waste material from the road's construction, and at some points you actually have to cross the road.
The people that drive up there also admit that while the place is ideal to go with kids, it is so crowded that it makes the experience miserable.
Finally, it didn't create a continuous economic revenue for anyone, since the lands are public and the town doesn't charge any fee. There are only a handful of shops in town and they have not seen an increase in consumption.
So what was the point of all it? Did we wreck a beautiful mountain and forest so that a construction company could pocket a few million euros?
A lot of national parks have this mix already. You can drive a scenic route. you can do a short interpretive walk or an accessible trail, or you can do a half- or full-day hike, or you can get out away from the main trails hiking 100 miles across the park. You can stay in a nearby town, or in the in-park campground, or hike 5 miles to a backcountry spot with no one around.
But I think accessibility would be one 'point of it all.'
-- Joseph Wood Krutch
If supply has a fixed upper limit and price is also fixed at a reasonable level, then demand will always peg to the right of the curve. The economic solution in this case is to increase supply (or increase cost)
This is only considered a problem when there is a real (or perceived) negative externality on increasing the supply. I fail to see the negative externality of having more national parks which massive numbers of people are very excited to tour.
The problem is purely that people concentrate in very small areas of that broader wilderness. Photo-driven tourism exacerbates this. People are inspired to travel by a photo they've seen, so spectacular things get buried in people.
If you want a wilder experience, it exists in almost every park, either outside of peak season, peak hour, or sometimes just a short distance off the main thoroughfares. The majority of people don't go beyond the easiest viewpoints.
Or just go in winter. It’s not hot, prices plummet, you don’t have to be up at stupid-o’clock for sunrise and there’s nobody around.
I think the ranger in The Maze mentioned that July had seriously low visitorship. Something like 7 people/day hiking in because of the heat and exposure?