I suppose the idea is that 'musics' is to music what 'wines' is to wine, i.e. types of. It seems to be a journalistic trait of our times to turn uncountable nouns into countables, as in 'an entertainment'. I think it sounds lousy.
By the way, if you're the real Kev Hopper I love your solo album. If not, I love his solo album.
― Japanese Giraffe (Japanese Giraffe), Tuesday, 27 July 2004 16:54 (twenty-one years ago)