I would venture this proposal: Vampires, Zombies, and the lot of monster-humans are especially interesting to people today because there is a rather special sense of change in today's world, change accompanied by mystery.
The advancement of computer technology coupled with the globalization of industry and a world-wide economic downturn has set the stage for a major shift in our lives. The degree of potential change does not automatically translate into big change, of course. Thirty years from now things may look very much the same as they looked five years ago.
The idea is interesting to me though to wonder if zombie afficianados feel, somewhere deep down, that what it means to be "human" is now being stretched and questioned in a general and generally cultural way.
Transformation is at the heart of vampire and zombie stories. Could it be that our ideas of what we will become has become somewhat garbled and one response to this, in young people especially (who have yet to create lives for themselves) is a fascination with magical transformation?
These transformations are, after all, a lot like discoveries, revelations of a true and potent self.