Vampires fighting Werewolves isn't knew, people starting talking about it in the 1940's when they were making early wolfman and Dracula movies. Hell I remember an episode of the animated ghost busters featuring both werewolves and vampires.
And really your argument would work better for underworld and only if we could actually romance Serana.
Your avatar is not allowed...
Something about that face makes me want to slap it.