Cops make mistakes. Occasionally fatal. Collectively we have the right to expect the highest level of performance from the people to whom we give badges and guns. And collectively we should err on the side of protecting society when a bad cop is discovered. When I worked in Houston, there was a youngish officer who had shot and killed four young black men. Statistically, there are lottery odds against that happened in the normal course of events. Turned out he was looking for trouble, and finding it. At the time, HPD was a rogue and didn't come into line with accepted police practices 'till mayor Whitmire brought in Lee Brown from Atlanta to be chief.
But there is a difference between guarding against police over reaction and incompetence and mindless, statistically insignificant episodes of bad policing. And anti-cop rhetoric. Millions upon millions of interactions between cops and civilians every year. And only a handful (thankfully) of these horrible outcomes. Police work, even absolutely by the book police work, sometimes looks very ugly. As an alternative, how 'bout the next time one of you whiners is being jacked up by a street punk, you call Mr. Lipschitz from the ACLU. I'm sure he'll be right over, with his Miranda card.