And as far as "not necessary" the game would be fairly boring without any of that kind of feature. So while melee combat > vampires or magic use > vampires, I could not say trolls > vampires, or even dragons > vampires, although I'm sure many people would (not nearly all of them, though).
They are good as high level monsters, being more powerful than natural foes, and as I've said before are well represented across history and cultures. Also, because both monsters are human in nature, it adds that special twist. And being able to play as one is actually one thing that can be used to define TES from other RPGS...there are other games that let you play a vampire, but none that let you choose if that is a vampire archer, swordsman, mage, live in an open world, and eventually get cured.
Very well said!
I also fail to see any particular connection between anime and vampires and werebeasts, although of course inspiration can be drawn from any number of sources.
I suggest vampire fans read http://en.wikipedia.org/wiki/Carmilla (it's in the public domain, and can be freely downloaded http://www.manybooks.net/titles/fanujose10001000710007-8.html). It's much older, and much better than most of the fiction people think of when vampires are mentioned.