That and, as you've mentioned before, the characters aren't really someone you feel bad about murdering.. It's strange, 'cause in NV there's not really a consequence either, but in that game I really tried hard to always think ahead and weigh my decisions based on their impact on the whole or individuals. There's just something about Bethesda (and Rockstar) games that make me go all Leeeeeeroy Jenkins - not a criticism though, that kinda playstyle can be fun and liberating.
Edit: Interestingly, I have 2 friends who are always complete **** in RPG (both game and tabletop) and they tell me that they are actually a lot nicer when playing Skyrim.. hmm..