Diminishing returns.  It comes down to personal tastes, but I find 
that even good fanfics have a limited number of things to say.  If 
everything can be said in 20K it's more interesting than expanding it 
to 500K, IMHO.

	Lack of experience (in reading).

I'm surprised by this observation.  Are you saying by this that there 
is no such thing as a good fanfic novel, or simply that most fanfic 
writers are incapable of writing one?

	Has anybody read 'After Dream', an urusei-yatsura
fanfic that very well qualifies as a novel. I can't remember
right now who wrote it, but it's wonderful. I very much
recommend it to anybody.

-RangerElf