I generally agree with your sentiment, but this statement right here I'm going to comment on. Police are trained extensively to do exactly what your claiming is not to be done. They are trained to responsibly use their firearm. They are trained to use it to diffuse dangerous scenarios, which may involve them actually pointing a gun without shooting it.
Although to your point, it appears that many police officers can't help themselves when presented on opportunity where their gun seems like the only option they have in their mind.
Except, police are trained to shoot if there is an "objectively reasonable" threat. This is why police can get away with shooting victims who are "reaching," even if no weapon is present.