I don't really agree that it's an "almost song". The amount of information it gives depends on your understanding of the context in which it is sung. This song is just very context-dependent but there is an awful lot of context.
Try Chaucer's student's tale or "The Miller's Will" for the background about millers. There are numerous songs about tailors (one of the best skits is called Benjamin Bowmanay - I don't know if it's in DT). Songs about weavers are usually pretty kind but that's because they mostly date from the Industrial Revolution where they were regarded as having been treated harshly. Mediaeval stereotypes were not so complimentary.
This song is worth serious study as it is a pointer to a whole range of Mediaeval attitudes to trades. Butchers, for example, usually get a good press - anyone know why?