@ Sicarius
(I only read the first three sources, but thank you for taking the time to look up all of those. Also, thank you for not including Wikipedia)
I think that police departments should have access to (and be able to use, if the situation requires) military-grade weapons. Criminals can easily obtain automatic assault rifles, so why should we care if police officers do? Technological advances have caused the arms race between police and criminals, not police militarization. In the 1950s and 1960s, criminals would not have anything more powerful than a hunting rifle, a pump-action shotgun, revolver, or semiautomatic pistol. During those years (and previous years) the venerable (but relatively weak) .38 Special revolver was a match for the crooks of the day. Now, thugs can get their hands on AR-15s, submachine guns, and semiautomatic shotguns. It is the police's responsibility to protect civilians from criminals. How are they going to protect civilians if criminals have them outgunned?
I believe it is better to use too much force than not enough.