If you're not breaking the law, why can't you expect to be safe? That's the main point.
If someone punched me in the street, I'd make every attempt to not be hurt again, even at the expense at the attacker. If someone if prepared to attack me, who knows how far he is prepared to go?
If someone broke into my home, why should I, a law abiding citizen, not be able to feel safe? I'd make any attempt to regain safety, even at the expense of the burglar. I'm not saying instantly go for the kill.