I agree there are positives for defense, but one persons defense is seen by another person as offense.
Since we can all be on the receiving end of the "defense", and errors can happen.
I worry about being killed on a picnic in the woods or hunted in my home by an identification error.
I don't want to throw out the baby with the bath water, but see this as a put on the brakes moment, as the technology is developing faster then our human ability to control it.