But certain techniques and production styles that narrative filmmaking allows (and that I personally employ) are usually looked down upon in documentary as distortions of reality. These techniques-- thin depth of field, dramatic music, heavy color grading, etc.-- are not distortions; rather, they accentuate and bring the film's reality closer to how we perceive our own. When you remember a particularly emotional or traumatic event, you don't remember how it "actually" happened, but rather you recall certain elements that your mind chooses to isolate. The freedom that narrative gives us, both in production and post, to "accentuate" in this manner can be used to bring Mr. Moviegoer into that "real" headspace we yearn for.
I believe good film works on an un/subconscious level just as much (if not more) than on a conscious one. Documentary rarely allows for this type of manipulation to the extent of narrative, and it's for this reason if nothing else that I prefer the latter.