Why are the film adaptations of Harry Potter good but the novelisations of the Star Wars films not?

I have this theory which has almost no justification or evidence to support it but which I hold to be almost inviolably true. Adaptations of stories from one media to another can be an improvement or a degradation of the story and whether the story is elevated or degenerated by adaptation is almost wholly dependent upon which media it is adapted from and to.
Here’s the diagram…
My argument is simply that if an adaptation follows the arrows (i.e. moves downwards) then it stands a reasonable chance of being a decent piece of story. Any adaptation made against the flow of the arrows (i.e. upwards) is almost certainly doomed to fail or at the very most treated as an entertaining but needless work. Oh, and musicals are bad. It doesn’t matter what you do with them or where they’re adapted from. They’re just wrong.
This might be a universal truth or a flawed personal theory generated by being forced to watch stage adaptations of Brassed Off and Mary Poppins (book to film to stage), reading the science fiction novelisations by Alan Dean Foster and seeing the tragedy that was Planet of the Apes on TV (book to film to TV).
“Pssst. Iain. What has this got to do with Mr Clovenhoof?”
Er, not sure. I guess I’m just thinking that if any forward-thinking Head of BBC Comedy or Hollywood exec wishes to commission a movie or TV adaptation then we’re open to negotiation. But if, in years to come, you see a poster advertising Mr Clovenhoof: The Stage Musical, you have my permission to slap me very very hard.
Yes, that’s it.
Posted in 2011, Reflections Tagged with: ,