I think that sometimes, if you utterly adore books, it becomes easy to imagine writers as these idealized creatures. And writers lend themselves to that by being more of a blank slate than other sorts of "celebrities" because they aren't often featured in entertainment shows and magazines.
I also think that people -- particularly kids -- who feel alone or isolated by their intellect or imaginations idealize and project traits onto the writers of their favorite books as a way to feel less alone. And, maybe, that isn't bad as long as one grows out of it.
Some things are kind of sweet at a certain age and a bit creepy in an older person. (I'd give examples but I just know I would be stomping on someone's fetish somewhere...)