So bold adventurers you have courageously fought your way into the Temple of the Bad Stuff while being beset by traps and ambushes set by the clever and evil orks who inhabit the place. Leaving a nearly endless trail of corpses in your wake you descend one final staircase into the heart of evil, ready to use your bloodstained axes to decapitate whatever fiend you find there. Now as you open the door you see (dramatic pause) a whole bunch of orcish babies and their caregivers hiding trembling in the corner of the room, obviously terrified of the maelstrom of death that you represent. What do you do?
This is the sort of dilemma I really enjoy putting into my games when I GM a fantasy RPG. For one it can generate really interesting conflict and discussion between characters and for two it makes them understand that the world is actually nuanced. If every orc in the world is a bloodthirsty maniac intent on attacking the characters on sight then surely the characters are justified in acting like murderhobos but when the orcs have guards and militias to defend their homes and families just like everybody else things become much more muddled.
There is nothing wrong with some things being just inherently evil monsters whether they be bloodsucking undead, voidspawn, demons, or whatever else but to my mind it really pays to have some ambiguity in most situations. There doesn't need to be a particular penalty or reward associated with challenging moral choices either - sometimes you let the scout you captured go and sometimes you kill them. Occasionally those choices should matter change the story arc but sometimes all they need to be is a bit of worry, regret, or relief and a powerful moment to remember the campaign by.
The most classic DnD is pretty much just an endless dungeon crawl where everything is out to kill you and nothing makes sense. I am not so much a fan of such things as if I want to play a pure tactical game I feel like I can do better than DnD and if I am roleplaying I want the world to be consistent and to challenge me. Randomly smashing into people's houses to kill them and take their stuff so that I can smash into the houses of more powerful people doesn't strike me as consistent with being a moral and righteous hero, nor does it make for interesting decisions.
James Wyatt wrote an interesting piece on that today where he talked about worldbuilding and making decisions about things like "Do orcs even have babies?" and "Are orcs inherently evil or are they just often socialized that way?" I think these are fantastic questions to have the answers to before you ever set out to run an adventure. For example, orks in Heroes By Trade are available as a player character race and aren't evil. They are scary, domineering, and militaristic by nature but killing them on sight is not at all justifiable morally. They also have females that are bigger than males, who make up 10% of the population, and who are the ones in charge most of the time so they definitely have some interesting quirks and aren't just people that the characters can mow down without any qualms.
This came up in my game last week where the characters fought a couple of patrols outside a Troll city underground and then snuck into the Troll city itself. They wandered up to the top floor of a building and kicked open the door, ready for a bloody brawl. Instead they found a couple of Troll adults, a handful of children, a pet 'dog', and a strange looking boxy device the children were messing with. The characters panicked a bit but then decided to run into the room, steal the strange device, and run out again. After a moment's inspection they determined that they had in fact stolen a children's toy and elected to run away. You seriously cannot make this kind of thing up; the brave heroes sneak into an enemy stronghold to steal toys from wailing children while making what seemed to be reasonable decisions at each step.