I doubt anyone would have gone to see FotR on the back of Heavenly Creatures, the audience is very different! I should imagine that many went because they wanted to see whether Jackson had managed to 'film the unfilmable'. But before the films came out there was an acknowledgement that they would have to secure the Tolkien fans' buy in if the films were to be a success.
Fan buy-in is always a known factor with this kind of film. And why these types of films which come on the back of a book with a massive cult following are incredibly hard to make. Look at the various films of Alan Moore's work (he famously refuses to have anything to do with them, he takes the Chris T approach!) - Watchmen secured the fans' approval and was a success, whereas The League of Extraordinary Gentlemen was not, despite being a decent film if you were not already a fan of the comic book.
Then you also get the kinds of fans who will go and see them whether they are keen or not, it's just something they need to appraise for themselves. I'll go and see them even if they
are bad films (and I think they will be very enjoyable, so I don't have that worry), just as I lap up Doctor Who even though I'm really not very keen on what Moffat is doing with it - it's just that I
prefer RTD's work, much as I
prefer the books to the films.
As for people who have only seen the films and think they speak with authority, that's just an ideal chance for me to spread the gospel
