This is what the LORD Almighty says: ‘I will punish the Amalekites for what they did to Israel when they waylaid them as they came up from Egypt. Now go, attack the Amalekites and totally destroy everything that belongs to them. Do not spare them; put to death men and women, children and infants, cattle and sheep, camels and donkeys.’ (1 Sam 15:1-3)
Every so often I see a post or a reply, on reddit or on other RPG forums, where someone raises a question like: "What about the innocent orc women and children? Isn't it just as 'evil' to kill them as it is for the orcs to kill humans?" Some people like to pose this as an ethical dilemma for their characters, while others use it as a reason to critice D&D's alignment system. Saving the alignment criticism for another day, I have a question: in a fantasy world where Good and Evil do exist, why is it hard to imagine a species that is always one or the other?
Some people think it's just a matter of making shoot-and-loot games easier to justify, because Evil becomes a target that you don't have to think about. But I think there's much more to it than that. One advantage of thinking of orcs or goblins or other humanoids as existentially Evil is that it makes them truly fantastic creatures. It also makes them horrific, because if they're otherwise like people but lack any capacity for Goodness (however you choose to define it), then that means they're really monsters and not just people in boogeyman suits.
Conversely, in a game where we wanted to explore, say, the shortcomings of xenophobia, we could create our own non-human race, the individual members of which may be any alignment. I feel that this is arguably a better route, rather than shoehorning kobolds and bugbears into roles that they were not intended to fill.
And if people want to play out ethical dilemmas in-game, why not have them play them out against NPC humans? The definition of Neutral is sufficiently broad that it can encompass plenty of people that you'd like to be out of the way forever, but couldn't justify slaying. For that matter, some people may be Evil, but their transgressions don't rise to a criminal or atrocious level worthy of meting out bloody justice.
I've dealt with the "goblin baby" problem a couple of ways in my games: in one, goblins were human once, but through their cruel and violent ways they fell out with most people and wandered into a realm where Evil corrupted their bodies and souls. Their transformation, moreover, is voluntary: they know full well that it is an evil and irreversible act. Alternately, these non-humans are spawned by magic or powerful entities solely for the purpose of doing their bidding. In neither case can you ever run into an "innocent goblin baby".
Although I realize that others don't see it this way, I've got to say it works well for me. It does make the game faster paced, and like I say, if I want to include ethical dilemmas in a game, I reserve that for humans or other non-goblinoid races.