Trivia: David Lynch was disgusted with the elongated cut of the film which includes paintings of the 'robot revolt' back story to the original film, a sub-plot he deliberately omitted. He demanded his name be removed from the credits of the film and replaced with the Director's Guild nom de plume, 'Alan Smithee'. This was done so sloppily, by superimposing Smithee's name over Lynch's, that the credit reads "A ALAN SMITHEE FILM".
Trivia: The tendons on the worm when it gets hooked by Paul are made from condoms.
Trivia: The TV version of this film lists a Mr. 'Judas Booth' as the screenwriter. Allegedly this was to get back at David Lynch (who was both screen writer and director) for so brutally condemning and demanding that all credits to him be removed from the film's re-edit for TV. The name is a combination of Judas Iscariot, the betrayer of Jesus, and Abraham Lincoln's killer, John Wilkes Booth.
Trivia: Director David Lynch has a cameo as a radio operator on a spice harvester, the crew of which are rescued from a sand worm by Duke Leto, Paul, Gurney, and Dr. Kynes.
Answer: Because it was edited in a way he didn't approve of. The film was actually over 3 hours long, and it was trimmed by about an hour for the cinema version, and then a certain amount of pick and mix went on to come up with the video version.
David Mercier