That list for the most part contains parks that cannot be reached by most folks: in Alaska with little or no road access or obscure political history sites that darned few people are interested in, Eugene O'Neil? Who cares about that?
Alibates Flint Quarries we've been a couple times to and unless they've upgraded the visitor center it's no wonder it is little visited. IIRC the trailer/visitor center was open an hour or two a day and they had one tour/day. Miss that slot and you are out of luck. Plus they had a very unfriendly ranger.
We missed the witching hour on our last trip and drove around the park to see what could be seen...just about nothing. An 8 foot fence blocked the view of the actual quarry. The ranger not having time to stop and ask us if she could help did have time to follow us around glaring at us for no apparent reason.
I guess she was very worried that we would steal a rock. She actually followed us out of the park property onto other federal land talking into her radio. We never did figure that out.
