I suppose you could use that for stylistic effect. Like a change of mood in the story, or a changed attitude of the character.
The Wizard of Oz did this with black and white / color.
That would be really interesting. I could imagine that being used in something like Requiem for a Dream to make things feel slightly off.
That's exactly the approach that Douglas Trumbull wanted to use in Brainstorm where the replayed experiences of others would have been displayed using his 60fps Showscan techbology: