I think you are right about the striking a basic chord in people. To be honest, it just mostly puzzles me, but what I have seen/heard elsewhere suggests people have reacted very strongly negative.

Having written a book or two and edited other people's fiction, I too find that line between fact and fiction very fluid, and indeed I presumed it was true of most writers. As a piece of fiction sounds like his work was outstanding, and doing what we as a society pretty much require of our fiction - it drew people in, opened their eyes, inspired them, made them care about the characters.