(Full disclosure, I'm sure this is more an issue for me, with my wanting more realism in characters and plot than realism in rules.
I've know played in three sessions of Dungeon World and I've been enjoying them but last night I realized that there was something that kept me (yes, I managed to let the group decide I was their leader, must to my chagrin) from leading the group full force ahead into adventure. The premise of the game is a modern day Twin Cities metro, but with magic and dungeons, where Adventuring Companies (emphasis on the company) send adventurers into dungeons but otherwise it's straight forward fantasy version of the present. The GM was explicit that the normal humanoid fantasy races, goblin, orc, kobold, weren't inherently evil, and that is leading to some quandaries. I had gone in expecting a fairly lighthearted game, and tenor of play-wise, it's been fairly lighthearted but the plot has been drifting much grittier.
In the first two session, the party, with the conceit that we were the local "neighborhood watch" went into a dungeon near a graveyard and fought a mixture of goblins and an elf (or two, I don't rightly recall if there was more than one) who were in what the GM described as a teenage party pad (wrecked furniture, oil barrel fire, empty keg) and while the elf was a member of a previous adventuring party to disappear into the dungeon, the goblins were definitely high school kids, ya know, wearing letter jackets and such. Now, there was a lower level of that dungeon with a definitely evil undead creature of some kind, so I think we partly rationalized things as "oh yeah, the evil undead thing was controlling them, so we're not total murder hobos for slaughtering those unarmed teenagers".