Excellent article. I've nothing against fan fiction at all. Some of it is very good, including the mainstream, traditionally published fan fiction. Anthony Horowitz's James Bond or Sherlock Holmes novels, for instance. Or Wide Sargasso Sea by Jean Rhys, which is a fine Jane Eyre companion piece. Or even something like Rozencrantz and Guildenstern are Dead by Tom Stoppard.

Personally, I prefer to write my own stories and characters, but I have occasionally indulged in outlines for what might have been where I've been dissatisfied. Here's what I would have done with the Star Wars prequels, for instance.