You just made my point for me. It's your right to defend yourself and disable your attacker, not to just "shrug it off".
It's my duty to society to be civilized and not squish like a bug anyone who crosses me. It also seems wrong to use my power (physical strength, in this case) in retaliation for a brief emotional outburst. We sometimes argue with those we care about, and should try to moderate our response. Those who would maliciously harm us deserve the best (or worst, depending on POV) malice we can dream up.
So, I guess I agree with you, I just couldn't see where you were coming from or going with all this. Best Wishes, Good Will, and Good Night. :-)
It's not just about retaliation. You don't know that your attacker isn't going to come after you with weapons or injure you somehow. Once you're attacked, it's your right to stop him or her before he or she injures you. That's my only point there.