The only way to decide if police are over- or under-militarized is whether they're doing things you like.
Police in 'sanctuary cities' should be de-militarized because civilian leaders have decided to turn away from the rule of law. Police would then only be tasked to count the dead bodies, and otherwise not get killed while trying to civilize the barbaric.
But that's just me. Maybe Trump supporters might need a military response, but that's a figment.