but one could argue we're trending back that way just with more expensive and deadly military toys.
This is part of what would make me dispute your "best ever" position (even though I'm usually the one arguing this position!) along with expanded and generally unchecked powers regarding unjust warrants, massive immunity, asset forfeiture, etc.
I think there's an argument to be made that a police force that roughs you up a little or shakes you down as part of regular corruption is a different beast than one who will burst unannounced into your home in the wee hours, set your child's bed on fire and unload a hundred rounds into you. Because you lived next door to a suspected drug dealer. Maybe, if you were on another road.
A smaller corrupt police force can be outsized and often was, at least to where it had to "play by certain rules" (even something as basic as Miranda) whereas the modern military forces that act almost entirely in an arbitrary manner, have no accountability and fund their overseers are different breed altogether. Especially when their interests align:
“I have my own army in the NYPD, which is the seventh biggest army in the world. I have my own State Department, much to Foggy Bottom’s annoyance. We have the United Nations in New York, and so we have an entree into the diplomatic world that Washington does not have,” Mayor Bloomberg said.