Any movie based upon any book (of depth) is going to have problems with what to cut. Every friend of mine had something they loved cut out of "The Lord of the Rings." I watched an excellent version of "Sense and Sensibility" (Emma Thompson's) and recalled missing something, but it was so long ago I don't recall what.

What is important is that the movie catch the spirit of the book, which was why I think Jackson's greatest sin was not of omission, but of commission, in that he made the dwarf the butt of jokes, even changing dwarven abilities to throw in another joke at Gimli's expense. Of course, as a slightly shorter and stockier guy who used to have a beard, I might have taken them personally.

It is also why I cut "I, Robot" more slack than my friends did. The movie wasn't dealing with a book as much as a whole collection of works. Most of Asimov's robot stories were short stories. But the main ideas of robot psychology were all there, including the evolution of the zero law, even if in Asimov's work that lead to different results.

I would also go out on a limb and say that "Blade Runner" was better than the book upon which it was based, because it made more sense. The book read like someone from the Beat Generation trying his hand at SF.

The weirdest transition was with "Starship Troopers." I'd never seen a movie apparently written to make fun of the book it came from. At least, that's the only explanation I can think of for those recruitment commericials and neo-Nazi symbolism.

Paul: For some reason I still haven't seen Starship Troopers, but I've long loved the movie in an abstract sense for that very fact. In my opinion, in many ways the book is Heinlen at his most objectionable, and I had a hard time swallowing the points he was trying to pass off as self-evident.

As per the article in general, it reminds me of the Asimov-approved screenplay by Harlan Ellison, the published book of which includes a rather thoughtful introduction. Both Ellison and Asimov understood that movies were an entirely different art from, and Ellison's treatment took the sorts of ideas that Asimov had played with and wrote them out for the movie screen, thus in a way being a more spiritually faithful adaptation than rote retellings often are.

I cannot find my copy of the book, but the I, Robot wikipedia page has a rather excellent comment from Asimov regarding the nature of Sci-Fi on the screen, published in 1983:

Eye-sci-fi has an audience that is fundamentally different from that of science fiction. In order for eye-sci-fi to be profitable it must be seen by tens of millions of people; in order for science fiction to be profitable it need be read by only tens of thousands of people. This means that some ninety percent (perhaps as much as ninety-nine percent) of the people who go to see eye-sci-fi are likely never to have read science fiction. The purveyors of eye-sci-fi cannot assume that their audience knows anything about science, has any experience with the scientific imagination, or even has any interest in science fiction.

But, in that case, why should the purveyors of eye-sci-fi expect anyone to see the pictures? Because they intend to supply something that has no essential connection with science fiction, but that tens of millions of people are willing to pay money to see. What is that? Why, scenes of destruction.

You can have spaceships destroying spaceships, monsters destroying cities, comets destroying the Earth. These are called 'special effects' and it is what people go for. A piece of eye-sci-fi without destruction is, I think, almost unheard of. If such a thing were made, no one would go to see it; or, if it were so good that it would indeed pull a small audience, it would not be thought of as science fiction of any kind.

Meanwhile I'd say that Asimov's works would be utterly brilliant as plays or radio series; when one creates something in a medium it tends to be, well, suited for that medium! (Fancy that.) If a book happens to be easily translatable into a good movie it's more of a coincidence than anything (or perhaps the case of a writer imagining a movie but spitting out a novel).

That being said, someone in the comments of the linked story mentioned that novels might be better suited for series adaptations, as in a set of 20-some episodes, and this is something I've often thought myself. Conversely, sometimes sections of television shows like the fourth season of Angel (or the more consistent sections of Battlestar Galactica) feel like the audio/visual form of a novel, with each episode a chapter or two.