As much as I hate to say it, I believe Williams shares a large portion of the responsibility for what happened to his film. He himself couldn't settle upon any one storyline, and when you have people dumping money into your project, you must get your act together. He got funding, and he had a chance to get it done. And he didn't do it.
Miramax certainly didn't need to rape it like they did. But it's obvious that Williams wasn't an innocent in all of this.