Who should narrate?

Watching Cory Scholl's television stories, I noticed something about the narration. Some of the videos had a faceless narrator, I assume the journalist, and others just had the subjects themselves speak.

The story on inner-city handball, for example, was one that relied solely on the words of the players themselves. One explained why they were there and what they did.

For more complex stories, like that of the storm or the fallen marines, I understand why the journalist chose to use a "floating" voice to lead in the story and fill in the details.

Those stories that stood on their own, however, left a pure image of the story in my mind. None of the stories overused narration, I thought, but on the other hand those with no narration were superior in my mind.