I actually have a serious question:
As a Vampire Lord, you can go and kill everyone in a town, like Riverwood, but what about in future DLC basically, you could kill everyone in Skyrim........there would be no one left
I have like 200+ hours on it and still haven't explored enough to have found all the settlements, and hey, you'll always have a bunch of kids to keep you company.
I suppose if you do that though, it's your own fault if you can't start quests later on.