Why Don't We Have More of These?

At the library today, I saw a copy of "The Werewolf Guide to Living". It presents itself as a nonfiction guide for new lycanthropes to adjust to their state, somewhat like the "Zombie Survival Guide".

It's written a lot better than the Zombie Survival Guide.

So why haven't we gotten more books on this line instead of the waves upon waves of classic-lit-with-supernatural-monsters crap?