Phil, as they say, the best is the enemy of the good. It's not a perfect solution, but better than nothing. The money would supposedly go to enforcement, although we all know that some of it will be siphoned off for other uses. It beats doing nothing.
And I would not want to see this jacked up out of sight so that all lower income folks would be screened out. The proposed $70 national park DAILY fee would accomplish exactly that. Very unfair (except for those of us with senior passes, like me).
I would say that a modest annual boondocking fee is far different in intent and effect.
It's not going to happen, though. Very few of us are in favor of it. And of course the government will listen to the majority, right? ;)
