"Our modern societies keep working toward very efficient and accurate ways to kill one another"
We could always go back to the less accurate ways of killing each other like a good old fashion Viking raid, barbarian hordes, firebombing cities Dresden style, concentration camps, and let's not forget Fatman & Little Boy.
I'd say it's not mutually exclusive. The sudden ability to take out those whom your government feels is "doing wrong" without being concerned about potential collateral damage is a new thing indeed. It makes war more palatable, less like the atrocities you describe above. That said, access to this kind of small, accurate technology considerably lowers the threshold between deciding to kill someone, and implementing that decision. At least I like to assume that the probability of wide spread collateral damage makes the decision harder to make.
The problem lies in the fact that "both sides" will eventually have this technology, and that the notion of "doing wrong" is unfortunately subjective.
We could always go back to the less accurate ways of killing each other like a good old fashion Viking raid, barbarian hordes, firebombing cities Dresden style, concentration camps, and let's not forget Fatman & Little Boy.