I think there should be a balance between dialogue that moves the story along and dialogue that gives insight to the character itself.

Of course unnecessary dialogue might have to be cut out if it's something professional but at the same time people don't talk like robots. We make jokes. Our voices crack. We repeat the same words over and over. We make short sentences. We make long sentences. Our speech patterns are relative, unique to every person.

Dialogue can allow you to show personality; to help lighten the mood, to help cultuvate character relationships. Even if it isn't furthering the plot, it's furthering your characters' depth, and helping your readers root for the characters.