I think that vampires have always had a certain sexual, darkly sensual, erotic overtone to the blood lust... Even back in the original Bela Lugosi days. Heaving bosoms, and dark dangerous men that come into your room at night to feast on your life force. That's hot! (ok, in concept... LOL).
Granted, I agree that vampires were never meant to "sparkle", but its a new interpretation for the teen generation... a softer 'emo' vampire. It's just a new incarnation of the same old story that gets most women excited.
I, for one, have had a bit of a 'dracula crush' for as far back as I can remember. Then again, I have an uber-sensitive neck region as well. There is something about a dominant, dark and overwhelming stranger causing women to throw away all inhibitions that has always been meant to be erotic.
Even in Bram Stoker's book, there was a lot of sex and lust going on...
The scary blood and fangs bit just heightens the danger... but it's still sexy as hell! (no pun intended).
Vampires are so yesterday. It's all about the Zombies now.