That page is pretty interesting Scott.
I've also been bothered lately, not especially by the lack of public lands in CO, but by the necessity for so many regulations in many public areas. I realize that these regulations are a product of an exponential increase in use due to tourism etc... but it bothers me that I have to buy a permit to access certain wilderness areas. It really seems that wilderness areas and other public lands are being overrun, especially in the northern areas of the state. But I digress... I'm off topic here.
On topic: I am of the opinion that it is not only legal for the ranch owners to charge an access fee, but also well within any moral or ethical standard (I honestly don't know what morals or ethics have to do with this, but that is the terminology that people seem to be using regarding this issue). I feel that this situation is absolutely comparable to the example that many others have given; what if you own a piece of land where there is some feature that may or may not be important to you, but attracts the attention of thousands of others? No matter what this feature may be, I feel it is justified for the landowner to charge a fee for access. Just my .02.