This franchise could have been cast with anyone and it would have been hugely popular. The girls don't go for the story or the acting (lack thereof), they go because of the image they have of this sensationalist vamp emo garbage. They all want emo vamp boyfriends now that sparkle in the sun. Sad.
I'd like the explanation of how Taylor Lautner goes from the weedy Native American kid in Twilight to the uber buff tool in New Moon. A lot of the cast have that davoid of personality, blank stare, not much upstairs thing going on. I don't get the fascination with Kristin Stewart either, she can't act and she is not attractive unless you are into young dudes. Weird. The best acting comes from a few of the Cullum (spelling?) family (Ashley Greene, Peter Facinelli, Jackson Rathbone, Kellan Lutz). The rest are pretty much negligible.
I expect many girls are drooling and having terribly dirty thoughts about the characters right at this very moment.