The 'regulars' will soon forget there are cameras and will continue to do their stupidity. But cameras can be really useful for after-the-facts investigations.
I'll also agree that a lot of stores, due to their own actions (or keeping a blind eye), attract the criminal's businesses.
Now I'm not sure about retroactively forcing stores to install cameras. I can see if new stores want a license to open, one requirement would be that they have camera(s). Same requirement for existing stores that are up for renewing their licenses.
Although many good citizens own and carry guns, keeping communities safe still fall on those who carry badges.
In a gun fight, even if you do everything right, you can still get killed.