[quote=@CyclicCynicism]do you believe killing should be relatively simple to ease the player's ability to connect with the game, or should it a much heavier subject to kind of make players feel like they're in a deeper, more realistic world?[/quote]

The more important questions address the external consequences, not the internal ones, if your greatest concerns are literary realism and worldbuilding. That is to say: when you kill a guy, what happens to his family? His friends and community? Did you just deprive a son of his father and a wife of her husband? Is anyone coming to you to claim vengeance? Will someone starve this winter because there's no longer a strong, able-bodied man to tend to the fields and harvest the crops?

Are [i]you[/i] the monster of this world, despite being the "protagonist," or is the death truly justified? He's not unimportant just because he's an NPC whose name you don't know. If your world truly is believable, and truly feels like real people live in it, then someone, somewhere, cared about this person's welfare, even if he only got two or three lines of characterization as another faceless mook mowed down by a player-character's blade.