If she’s carrying concealed on her person, or in a handbag, someone looking to grab a gun isn’t going to focus on her. Sure, if it’s in her handbag, someone looking for her wallet and credit cards might end up with a gun as a bonus, but it’s unlikely that such an accidental acquisition of a gun would lead the thief to commit any violent crimes that he wouldn’t otherwise have committed.
And note that I’m not suggesting it should be illegal to open-carry. Just that it’s generally unwise unless it’s a situation where your primary focus will be on providing security for yourself and others.
I split my time between NYC and Pennsylvania. When in Pennsylvania, I carry 100% of the time — a little Keltec P32 in an outer pocket of my shoulder bag. My shoulder bag is always over my shoulder, unless I really need to put it down, and then it goes between my feet, not slung over the back of a chair. I really don’t wan’t to lose my wallet, Blackberry, or gun.
If you are carrying period, that is pretty much your primary focus.
The deterrent value of a group of openly armed people is pretty damn obvious. Arguing the point is silly.