Scott Greenfield rightly bemoans law enforcement's use of robotics in situations that typically call for classic negotiation and conflict resolution. Cops de-escalate because a big part of the cost of a confrontation with armed bad dudes is the possibility of taking a ride home in a hearse. No one wants to eat lead, therefore wait the guy out, talk him down, or lay siege. Unfortunately, playing a waiting game with a desperado is expensive. Not only do showdowns incur direct payroll costs, but every officer stationed in a crouch behind a cruiser waiting for the madman to stand down is an officer not patrolling the community to maintain good law and order. Petty criminals get themselves a Roman holiday when some loony-pants starts shooting up a demonstration. In econ 101 terms, the use of a disposable weapon-bearing robot is relatively cheaper than the next best alternative.
Or at least in a one-shot interaction (pun unintentional). This one time, it's expedient to send in R2-D2 to blow up a bad guy so that we can all get back to our regular beat, or make it home in time to catch the last couple of innings, or whatever. The problem is that weapons systems have a bit of a tendency to metastasize. Military advantage is fleeting. Macedonian King Philip II believed that his armies' use of the ballista would mean the permanent end of warfare, since all other peoples would be so cowed by the mighty weapon that they would lay down their arms in the face of his superiority.
Cheap weapons-bearing robots mean that the relative price of doing harm from afar is dropping. This is as true for sovereign armies as for municipal police as for backyard hobbyists. Remember the killdozer? The 2016 version would have a Rasperry Pi and a mobile phone in lieu of a pilot. Or how about a quadrocopter swarm fitted with homebrew chemical weapons? Just imagine how many dishonorable, despicable ways wicked men might conjure to slay their foes once a) the price of remote murder drops sufficiently and b) the Overton window for assassination-by-remote opens. DPD officers might be obliged to confront some serious regrets once the renegade element decides that robotic combat is fair play.
Some genies can be corralled with strict control over production bottlenecks. The great expense of enriching uranium means that backyard nukes are probably forever unlikely. The same goes for hobbyist howitzers and tinkerer tanks. But little 3-D printed, remote-controlled drones? I urge you to remember which side shot first.