How is point of view important in Fahrenheit 451?
The entire novel is told from Montag's point of view, and this is crucial to the reader in understanding how he thinks and how his views change. At the beginning, even when Clarisse challenges his ideas, he is obstinate and sure of his morality; later, as his opinions evolve, he becomes less and less sure of himself, constantly second-guessing and worrying. By the end, Montag is in almost a constant state of feverish delirium, thinking that his hands and body move on their own, without his mental input.
It was a pleasure to burn.
It was a special pleasure to see things eaten, to see things blackened and changed.
...here was where the conscience first manifested itself to snatch books, dart off with Job and Ruth and Willie Shakespeare, and now, in the firehouse, these hands seemed gloved with blood.
(Bradbury, Fahrenheit 451, Google Books)
While there are long passages where the dialogue is dominated by another voice -- Clarisse, Beatty -- Montag's perception of events is the most important, and his view informs the reader. This allows insight into his mental processes, and into the way individualism slowly grows in his collectivist mindset; it also lets the underlying message of the book grow through dialogue and action, instead of through narration and exposition.