I would like to work on it, but I can't do too much due to having an exam in a couple of days. I would be willing to help with an expansion though.
So far we have:
This actually goes back pretty far, since vampirism has long been a metaphor for sexual activity in legends. (If we could get an early example here, that would be cool.)
(The very term "vamp" is an evolution of this metaphor.) Vampires' need for blood makes them animalistic predators (A quick explanation on why this is seen to be so?)
; therefore, their sexual needs are more basic and rougher, which can be something of a Fetish for some people, hence the expression, "necking". The other part of the Trope goes to the Victorian ideals of womanhood: pale, frail and bloodless, which was the effect of tuberculosis, aka "consumption", on women, which is part of where the vampire myth originated. Certainly a lot of vampires are Black And White Beauties. (A quick summary on which parts evolved here, and how they influenced media?)
The question of how vampires can be sexually active despite being clinically dead (in most settings), and what it says about the people attracted to them anyway, tends to be handwaved or played for squicky laughs (An example, the more popular the better, would be awesome here.)
. Other Undead such as Zombies tend not to get this treatment because it involves Squick (An explanation on why vampires don't, relating to earlier points could go here)
, and it's rare in a Fur Against Fang scenario or Vampire Werewolf Love Triangle for Werewolves to get the same treatment, as having a pale, nubile corset-clad young lady sip from your vein is sexy, whilst werewolves tend tp be associated more with the idea of being mauled to death and torn into tiny pieces and eaten by a Big Badass Wolf, rather than the idea of giving in to animalistic urges (especially sex) (And now an analysis on why the rougher aspects of vampires are played for sex, while other rough-and-tumble types, like Werewolves, don't.)
After that, just a quick examination of popular stories that use this- e.g. Dracula, Anne Rice and Twilight, and how it's evolved from there- would fit in nicely and provide perspective on how it's evolved and how society influenced this change.