I'm honestly glad Kubrick didn't go with Clarke's narration. Kubrick was a filmmaker and Clarke was a writer. While abstract and nearly impossible to understand without the book, the movie and book work amazingly well together as a unit. With concrete first order explanation at the end the sense of profundity wouldn't have been there. The aliens and their machines are vastly beyond human comprehension, and the arc of man's evolution was absolutely poetic. It would have been dated and corny with direct visual and vocal explication. The movie drew me to book, not the other way around.