Zombies have been driven into the ground. I get that they're an easy target because they're mindless, already dead humanoids that no one can disagree with them needing re-killing. They're like Nazis and Aliens which we can kill without guilt.
Notice that in almost all modern shooters, our targets rarely have uncovered, human faces. Even men and women will be masked with helmets or balaclavas and/or in some sort of uniform to dehumanise them. But still, zombies are done to death now. If there wasn't another zombie title for the next 5 years, then MAYBE we can think about re-xploring this area.
But Vampires rock. There's not been nearly enough of them in media, let alone games. Apart from the recent Dawnguard, what else in the last 3-4 years has had a vampire in it? Only vampiric games I have are TES series, VTM: Bloodlines and Bloodrayne series that is sorely in need of a sequel, though at this stage, I'd prefer to wait till next gen for it.
TES isn't really a vampire game though. Even when you are one, it's secondary, not particularly important to the game and mostly just for storyline/RP purposes. I would love another game like VTM: Bloodlines, but with more interaction and consequence. It had a great feeling of being undead among the living and vampire society, the need to feed and so on. Sadly CCP bought the license though so we'll never, ever see an offline game, just the MMO :-\
More vamps, less tramps! (I don't have anything against the homeless, they just happen to rhyme with "vamps").