2) Because there is no such thing as shoot to wound. If you've gotten to the point where you're shooting at someone they need to be dead. Any bullet holes in your body are potentially fatal. Especially the famous leg shot; damage to your femoral artery will kill you extremely quickly.
Some people have mental issues and normally they twitch a lot. And cops claim they were afraid for their lives, it’s the easy license to kill. I find that barbaric and no wonder we see so much backlash against the police force!!!
When considering whether or not the use of deadly force was justified in a given situation, the lack of a weapon isn't the trump card indicating the force was not justified that many people think it is.