There are certainly places where concealment of a firearms is a the more polite option -- Chipotle's Grill for example -- but, whenever the open carry versus concealed carry argument comes up, the Internet commandos will always claim a concealed firearm is a "tactical advantage". This is preferred because the bad guy doesn't know you're armed until it is too late. I've always found that argument a little dubious and my inclination is that open carry is a deterrent to an attack happening in the first place.
I know it is not an argument that will be settled anytime soon. Largely, I think, because there are a lot of unspoken assumptions on both sides. However, Greg Champion, a security guard in Detroit where violent carjacking has skyrocketed, offers his own reason for carrying openly.
To avoid becoming a victim, security guard Greg Champion wears a handgun on his hip whenever he's pumping gas.
"I don't want to surprise you," Champion said. "I want you to know I'm armed, and I want you to know I can defend myself, and I want you to go somewhere else."
A man after my own heart: I may not be able to make crime go away but I will try to make it go somewhere else.