Because you might have absolutely NO desire to carry/purchase a gun or even think about shooting something? You couldn't pay me to carry a gun.
It's okay that you feel like that because your government thinks of you as a criminal that only lacks a gun to be dangerous. When your government banned handguns for the average subject (they don't think of you as a citizen) the crime rate jumped. Why? Because criminals were the only ones that didn't turn thier guns in. Why? Because they are Criminals. Every type of violent crime is already illegal and they still happen, so how can passing a law against using a certain method be expected to help?