Why post-apocalypse through US zombie movies or Japanese kaiju anime?

http://youtu.be/ZEs33aWkX2Q

I just watched a review of the videogame "The Last of Us", and Sessler mentioned how it reiterates the post-apocalyptic themes, made popular by zombie movies. 

I was reminded of this TED talk on the zombie genre.  In it, Daniel Drezner related the increasing frequency of zombie movies to America's post-9/11 mindset.
http://www.youtube.com/watch?v=Vjke3VTp5ks&feature=share&list=PLbGXNMLue5g0fejoA1tVZWlocQv4ThKVl

 

If America is currently living in a post-apocalyptic shock, then I wonder how we handle it differently from the Japanese.  o.o? 

A great majority of anime is post-apocalyptic, and some documentaries have attributed this to Japan's experience of apocalypse in Real Life, when atomic bombs were dropped on them during World War II.  Many of these old anime in the post-apocalyptic genre do often explain their fictional worlds' apocalyptic event as atomic explosion, or at least use the same type of mushroom cloud imagery or similar type of destructive effects.  Pop culture stories also turned to atomic-influenced monsters, like Godzilla.  Then, just giant monsters, as in many tokusatsu shows or Neon Genesis Evangelion. 

It is only fairly recently that Japanese anime has expressed the post-apocalyptic genre through a zombie series, like High School of the Dead (HOTD).  (But HOTD seems more like a stand-alone experiment or homage to the American zombie genre, more than an effective trend.)  Why is that?  And why does the zombie genre work so well for us, to express our post-apocalyptic sentiments?  What is it about the American experience of "the apocalypse", as 9/11 seems to have been, that resonates so well with zombies?  While Japan seems to have dealt with their post-apocalyptic feelings through giant monsters or kaiju? 

I don't have answers.  I'm just posing a question.  I don't know enough about the details of the traumatic effects of the 9/11 attacks on American society's psychology as a whole.  I don't know what in Japanese culture or their society's psychology made giant monsters speak to their trauma, so much more than something like zombies.  I'm not an expert of zombie movies.  

Although it has been said by some documentaries that the zombie apocalypse is often characterized by a fall of civilization, government, and authority.  And without these, the characters in zombie movies often end up in just as much danger, from their fellow human survivors, if not more.  Even in non-zombie post-apocalypse movies like Mad Max.  This human threat also occurs in The Last of Us, from human survivors killing each other for resources, but also from the human authority figures in the post-apocalyptic world.  Does this say something about what the big fear is in the American cultural mindset?  Is this why the monster in American pop culture's cathartic discussion on apocalypse, look so human or was once human?  ...Whereas the monster embodying the Japanese post-apocalyptic discussion is often very inhuman?
I should stop now, before I continue anymore unfounded speculation.  ~.~;