Anthony, are you a UK fan? I see you are sporting a John Wall pic for your profile. I had a pair of cousins play there back in the day and I think I'm the lone Wildcat fan out here in Idaho.
Anyway, to answer your questions, I say "yes." It would rate higher for a couple of reasons. Conditioning would be better if it were private since the amount of play would be quite a bit less. The experience would be "purer" since I can't imagine they would allow all the random people to just walk around on the course like they do now. Also, you wouldn't have all the hustle of bustle of the course selling merchandise like crazy and hence would create a more private, intimate golf atmosphere. I think Pebble would be reverenced like Augusta. As far as the U.S. Open, I don't know if it would be any better or worse.