I'm not sure why you're so dismissive of moral relativism in this context when it's incredibly relevant. Someone who believes that developing and exploring this technology will enable us to save the lives of soldiers and better prepare to encounter the technology in the wild is going to have very different opinions than someone who views it as yet another tool to oppress the third world with. Both people hold ethical beliefs that consider and value humanitarian consequences.

Edit: I was slowed down for posting too fast so I'm adding my reply to IntronExon here:

It's an interesting hypothetical but I'd argue its appeal is mostly in its simplicity with little evidence to support the claim. The instances you've cited happened either due to a failure of accurate intelligence or because intelligence indicated the structure was being used by enemy combatants. It's very possible to arrive at the conclusion that any unnecessary casualties which occurred happened as a result of poor military intelligence which better reconnaissance drones could help with. It's equally possible that someone working on this kind of technology could see its field use against groups like ISIS as evidence that weaponized drones are a useful tool in fighting terrorist organizations. Obviously neither of these will be true in every instance, but without strong evidence it's hard to believe that the matter is as simple as "some people are just unemphatic".