Two reasons I’ve heard for concealed v open carry.
1. Some people, instead of having the reaction you did, are disturbed by others open carrying. While they know there are likely some concealed carry in public places, they don’t see the guns so they aren’t bothered by them. For me, a lot of the comfortable v disturbed reaction depends on who is doing the open carrying.
Recently saw a gentleman open carrying in Walmart, which is pretty odd here despite a ton of folks concealed carrying. The way he looked and general vibe he was giving off, I wouldn’t have been at all surprised to see him in the parking lot in an old white van without windows inviting little girls to stop by for candy. Dude was majorly creepy. His presence with pistol on hip did NOT make me more comfortable. If he was concealed carrying or not carrying he still would have been disturbing, but lack of a full size 1911 style something on his hip would have taken it down a couple notches.
2. If you’re not uniformed law
enforcement, someone obviously creating a high profile, you’re better off not letting everyone, including would be assailants, know you’re carrying.
For example, say you’re in a restaurant with 30 other people. Out of those 30, 5 are armed, 2 open carry and 3 concealed. A gunman enters the restaurant with intent to commit the latest mass shooting. If he has any logic remaining, who does he shoot first? Obviously those he knows are armed as they’re the only ones he knows can potentially effectively stop him. So far as he knows, 2 are open carrying and all of the other 28 may or may not be carrying.
Or you’re walking down a street and an assailant is planning to assault you. With open carry, two possibilities: good - sees you’re armed so skips you in favor of a softer target; or bad - sees you’re armed so is able to adapt his strategy to account for the need to disarm you or disable you before you can pull your gun.
Concealed retains the element of surprise, which can be a critical element in some scenarios, particularly defensive situations where you’re not on high alert and/or don’t know you’re in a fight until it’s already started.
That said, my experience with quite a few folks when queried about what they are doing on some part of our property, the mere fact that I happen to have shotgun or .308 slung on my shoulder or held in a completely non-aggressive manner results in amazing humility and manners grandma would be proud to see in church.
So maybe there’s something to be said for open carry. Probably not in public places where it’s highly abnormal, but if open carry is normal where you are, probably fine.