When I took intensive voice classes in graduate school, we were warned to never, ever, utilize vocal fry - it was bad for your voice. Whenever one of my classmates performed a monologue and slipped into "fry-zone," the professor would stop them or make a note. The reason? You have no power that far down in your registry...you're avoiding the deep emotional resonances that live in your "natural" range.
So...as always, the challenge for the voice actor is to adapt to the circumstance at hand! Be able to imitate this when necessary, but not to fall into it habitually :)