I see Open Carry (of a pistol on your hip in a holster, not some *expletive deleted*bag neckbeard with his AK at the the low ready in Starbucks) in three ways:
1. Deterrent effect. Most crimes aren't committed by "Criminal Masterminds*", but hood rats, meth-heads and other folks from the lower end of the bell curve. They are crimes of opportunity, not long-range strategic planning. They just might see you and re-think their "plan".
2. Normalizes guns. Folks that watch me chase my blind father through Wal-mart and Meijer get to see an ordinary person with a firearm. I smile a lot, am polite and friendly to everyone. A positive ambassador (but not a Companion) of the firearms culture.
3. I don't buy into the "They shoot you first." theory of "lost tactical advantage". Trying to rip away the cover garment and having it not get snagged takes real time and practice. Not to mention that said hood-rat/methhead will shoot you as your trying to hold your cover garment open. (yeah we all do dry fire drills, but trying to get your Gat from underneath your Hawaiian print shirt without it getting caught. Ugh.)
*- They prefer to smuggle bobble-headed Geisha dolls. Because people love those.