Fantasy literature, and thus games, have a long tradition of evil or villain races. Orcs being the classic example of such a race, though D&D has many: Orcs, Goblins and Hobgoblins, Kobolds, Drow and those are just the major ones!
These races are defined by their opposition to the forces of ‘Civilization’ and ‘Right’, that side being fixed by the fact that it is the side the Player Characters are on. One does not need to think about the fact that your character is slaughtering intelligent beings. They are Evil; no other justification is needed. This is something that has troubled me for some time. Cultures may be, more or less, evil but the idea that an entire group of intelligent beings is, just because of their genetics, always evil full stop is unreasonable.