I assume that it was there because there have been a lot of discussion about the morality of using drones as well as films like 'Eyes in the Sky'.
Other than showing the moral dilemma of the soldier and its psychological effects, that part of the story could have been removed and nobody would have missed it.
It could bring some debate over this type of war which looks more like a video game with fatal consequences. I might be over reading but I assume that the director or whoever is taking the decisions does not approve this.
It killed outright somebody who did not "deserve" to die. However, the other character, who "deserve" to die, is hit almost on his head but miraculously he is alive later on.
This i get, but why didn't they integrate it into the story, it just felt like a afterthought of 'oh wait we need a moral message' (which it didnt, as i thought it was told pretty well in the progression of the characters). Very odd.