The appropriate mood is important for the music, but so too is style and genre. Generic music is an easy way to communicate with the audience quickly because they will usually associate it with much of the archetypal history of that genre, even if they do not know a lot about it consciously. This is a form of symbolic representation, where you use a certain branch of music to associate the scene within a form of precedence or historical context. For example, if you are talking about the creation of a radical commune in the early sixties, having some psychedelic folk music in the background will immediately give it context.