I don't speak for anybody who is against it or the LEO's that are against open carry. These aren't even my viewpoints on open carry.
However, here are the reasons I recall that were given to me. Most of these reasons are typically given by LEO's in cities with large, diverse populations.
1) Conceal carry forces people to go through some sort of validation/verification process. Criminals won't go through that process and most would fail the background check anyways. This gives the LEO the relief knowing that if you get pulled over and you show them the permit, it's reasonable for them to assume that you can be trusted and are not a threat with a firearm.
Typically conceal carry holders are careful about concealing their weapon and getting basic training on gun safety. Criminals tend to be a bit more careless with their firearms. Chances are, if an individual is pulled over or stopped with a firearm without a permit, there's a good chance the individual has prior history, with warrants, ect. It makes it easier for LEO's to instantly apprehend criminals and take them off the streets outside of actually catching the criminal "in the criminal act." This is more true in city centers than out in smaller towns and in the country.
(unrestricted) Open carry removes that and now everybody good or bad may carry firearms. LEO's have told me that this will force LEO's to assume that every person open carrying is a hostile target unless proven otherwise. Alternatively, this increases hostile profiling of people open carrying based on location of city/state, ethinicity, ect.
2) It makes it hard for LEO's to discern who the bad guy is in a situation. Typically, anyone with a firearm is instantly zeroed in. With open carry, it makes it harder for them to do this because a gun does not mean bad anymore and takes retraining. It makes it harder for the LEO's to know who the good / bad guys are in a situation, especially if firearms are drawn. "Misunderstandings" between LEO's and citizens will increase.
3) For the most part, most people don't open carry, even in states where it's legal to do so. Because of that, you're dealing with a small percentage of the population so there is very little problems. The small percentage of the people who currently open carry are typically gun owners who are responsible and practice proper safety.
However, as with anything if that percentage of people who open carry goes up, numerous problems associated with open carry goes up exponentially. If the majority of the population were to open carry, then you have to factor in an exponential increase of "stupidity." Things like people open carrying while intoxicated or people firing on each other during a heated argument. You also open up to an increase of accidental discharges.
If enough of these incidents happen and there's proof of a higher increase of "stupidity" with firearms in correlation with open carry, kiss your 2nd amendment goodbye. It will only be a matter of time before there's an outcry from the media and populace about stricter gun control.
Anyways, those are some of the reasons communicated to me by various LEO's and and former LEO's I know. Not saying I agree with any or all of the reasons.
Glad you don't agree. I couldn't even pass along that load of crap without spewing.