Bethesda (or Bethesda Game Studios) isnt known for its dark endings. Most of their games arent even known for their endings; they are instead known for their sprawling open worlds, which are full of characters and side quests that seem designed to sidetrack the player. Its likely that most players, even more than what is already the norm for video games, dont finish Bethesda's RPGs. After all, even the more dedicated fans of those titles dont always complete their playthrough.