I agree with you Redsilver. I have never written a fic from a book thus far. My fandom is Final Fantasy and Resident Evil, but I think the same thing applies with games. I've inspired some of my readers to seek out and play the games I write fics for, because they liked my stories. So, in a way, I'm making more money for the makers of said games.
I would say the same about other fic writer friends, inspiring their readers to buy the book from the authors, thus gaining that published author a bigger fan base, and gaining more money.
My reasoning, why would they complain if fan fiction gains them more fans for their original works? If I was a published author, I think I would appreciate that. Not to mention the fact that no one gets paid for writing fan fiction.
Of course, adult fan fiction will always be frowned upon more than others.