So many people died when the attacker were unarmed. Hands are deadly too. Just look a the College student who killed his girlfriend. Only bare hands were used.
I myself was fascinated by this case of the law.
If I was attacked by one like Tyson, the famous boxer, I will try to run like a deer, failure of running, I may risk one punch or 2, then I will shoot 2-tap center mass.
I guess, the legislator stopped short of allowing deploying deadly force on unarmed subject as this will open a slippery slope for minor violent encounter that turns deadly. A recent case is the parking lot attendant who was shot and killed after a fist fight. He was armed, but by law could not deploy a deadly force.