I do not know about technical musical genre's. But such tunes are classified as "Show Tunes". I think this means that the music was originally just a part of something greater than a musical performance - such as a play, a circus performance, a movie etc.
I happen to like a lot of Show Tunes. They are not generated by record company executives to target a specific audience and they are not formula-driven by recording company heuristics. Instead they are composed to compliment some scene or performance and therefore are much more unique than music from some of the other more 'popular' genre.