Even if you argue they're on a power trip, enjoying what little power that they can personally exert in a system meant to crush all but the billionaires...
The option of murdering people freely should not be a coping mechanism we make available to psychopaths.
No license to kill. No more qualified immunity. No more armed cops everywhere.
The US should do like other countries, where only your special firearms officers are armed, and those make up a tiny on-demand portion of your force.