The actual use of force in police-public contact situations is a very low base rate phenomenon - generally less than 3%. In this context, use of force includes everything from hand & foot strikes up the continuum to lethal force. Lethal force, by itself, occurs in substantially less than 1% of P-P encounters.
Now to be sure, police officers generally have a very low threshold of tolerance for "contempt of cop" and are wont to see anything less than immediate compliance as resistance. Push gets push back and the officer ups the level of force in the encounter - say from a simple request to a command directive. Thereafter, the push by the officer will match and exceed that of the unruly citizen.
It is problematic with returning veterans, especially those who were LE before, during, and after deployment. I personally think those officers have a tougher time re-assimilating into civilian life than vets who return to joe-jobs. The problem is inherent in the differing rules of engagement. It takes an LE officer longer to spool up in-country and transition from a gradually escalating use of force where lethal action is to be avoided until it can't be avoided. In combat, this can be fatal. Once fully spooled up, it takes a similarly long time to decompress once back in the world.
So, I don't think it is so much the paramilitary nature of LE, its always been that way. However, the us-vs-them mentality can be very problematic. For many officers it is simply safer and easier to assume every citizen is a booger eater until proven otherwise.
In large, professional agencies, the tactical team members are typically among the most mature and professional. I do worry about the tac guys from Awshucks County SO, who got their toys on a Homeland Sec grant and decided not to waste money on training.
On balance, I'm okay with LE having automatic weapons. Crew served is a bit much assuming it was not an item originally held in evidence. The APCs make perfect sense - I've hidden in one or two myself whilst trying to convince some yahoo not to off his whole family and then himself.
I do, however, agree with Aarond on this point. LE works for the citizenry AND derives its very authority to use force from that citizenry.
"I'm your huckleberry."