As time goes on we get closer to that American Dream of there being a pie cut up and shared. Usually greed and selfishness prevent that and there is always one bad apple in every barrel.
I always thought of vampires, especially the young-adult ones, as a metaphor for sex - sucking blood, forbidden, taboo. I think they just ooze sex. Vampires are all the big themes in life in one attractive, bloodsucking package.