Shamelessly lifting this from a Brother at Lightfighter.net, because he said it far better than I could have.
Citizens must not be stripped of the ability to effectively counter criminal violence.
Because, the armed citizen faces the VERY SAME criminals that police face. The only difference is that police, because they are more often called TO the incident, face these criminals more regularly. Understand, though, criminals do not prey on police, but instead, they victimize the public.