Earlier quoted context omitted.
I personally tend to look down on people who read only non-fiction (though obviously not as much as people who don't read at all). It suggests a lack of imagination. And I think perhaps that's the self-improvement aspect of fiction - it exercises the imagination.
Right, because reading _Godel Escher Bach_, _Shock of the New_, and _Drawing on the Right Side of the Brain_ (my current reading list) obviously doesn't exercise the imagination.
EDIT: Ok, not all, just the ones in English. ;-)
And a further EDIT: all three of those books are about "Art" more or less. I can't see how someone who read those books can't read fiction. So I'm guessing you missed "only."