The most recent DBH post at First Things starts with a funny note about Mayan prophecies which include dates after 2012, and then asks an interesting question he leaves largely unanswered: Why the current vogue for post–apocalypticism?
The rise of the zombie genre in the last decade, for example, shows a really telling turning point. It began with some "re–imaginings" of the genre, most notably 28 Days Later in 2002. But there is an obvious change in tone with the Zombie Survival Guide in 2003, and its broader acceptance beyond communities of nerds and college guys (a pretty well overlapping demographic in the generation where sorority girls watch Battlestar: Galactica), once it was clear the economy was starting to sputter hard in 2007. (2009's Zombieland is kind of the cinematic summa of the new zombie genre, combining survivalist "tips" (not nearly as serious as Brooks's), the comedy tone of the "cross–overs" and nerd–romance/wish fulfillment.)
Simply put: People are fascinated by post–apocalyptic scenarios because of a general sense of "this can't go on", but need to have some sort of socially acceptable place to work out the thoughts, for those who aren't already into survivalist or pessimistic internet culture. Obviously this is part of the appeal in all generations, but the greater profile indicates greater resonance.