My only issue with open carry are with those who do so where it's inappropriate. If I'm at the range, or at a firearm friendly setting/area, I don't care if I print. I might even open carry. When I'm somewhere were open carry will cause trouble, bring unwanted attention, scare people, will disrupt business, or it's just inappropriate, I'll conceal carry out of respect for customers, the business owner and employees, etc. Other than that, I like to have the element of surprise and not being a target. Printing to the point where someone can tell you're carrying a gun just defeats the purpose of conceal carry.
There's also the assumption that people never notice printing or open carry just because no one said anything. In my experience, most people, even those who do not like guns, will not say anything even if they do notice or care.