So far as I can tell, 27 states allow you to carry without a permit. Several other states allow you to openly carry with a permit, so that is the majority of states. It seems that OC is not illegal in most places.Since OC is illegal most places, that might have a lot to do with your observation (which of course is nothing but anecdotal)
That being said, your other points about the percentage of people carrying, openly or not seems to have a deterrent effect upon criminals and crime. Getting shot is not pleasant. Seeing a gun on a well dressed person screams "COP!" to most people.
I see open carry as a way to promote safety, courtesy, and awareness of our rights. I've heard of the "down-side" to carrying openly, but have yet to hear of any credible fears of OC coming true. The majority of folks encountering OC individuals seems to be positive.