North Indian, South Indian, Hindustani, Carnatic, Film music from maybe a dozen different languages that are wildly different, qawwalis, ghazals, Rabindra Sangeet, music from different periods of Indian cinema... I could go on... sigh.
Insight is they are based off NY which makes they impervious to Indian laws. And personally, I haven't come across any good Indian website that gives you impression that you are buying legal content.
"You got to let that raga drop"
http://everynoise.com/engenremap.html
(look at the bottom of the cloud)
Some exposition here:
http://www.furia.com/page.cgi?type=log&id=392
and in other posts there.
Or you could slice it by form: "Hymns, Choirs, Quartets, Symphonies, Concertos, Sonatas, Operas, Ballets, Rondos, Minuets, Gavottes, Chaconnes, Themes & variations, Musicals, Film scores, Popular & rock music."
Or by instrument: "Harpsichord, Piano, harp, Violin, Viola, Cello, Flute, Oboe, Clarinet, French Horn, Bassoon, Trumpet, Trombone, Tuba, Guitar, Percussion, Electric Instruments".
I think the general point is that categories depend upon the listener. You can't impose a categorization on data without understanding who the audience is and what their mental model of the field is. And the more expertise you gain in a field, the deeper your categorization gets.
This is random, but one of the things I love about Civilization IV is that when you enter a new era, it plays music from that era, to really give you the sense of moving through time.
Except that when you enter the "Medieval" era, it plays this:
https://www.youtube.com/watch?v=7g7jOKLUus8
A brilliant piece of music, and a great credit to them that they would have chosen this piece and this recording of it. An absolute masterpiece. Of the High Renaissance, that is. Sheppard was born c. 1515, and the Renaissance in music is usually dated to begin somewhere around 1400.
I guess I'm saying you're not the only one. :)
You're just complaining then about what the top-level nodes are on the classification tree of music genres. If you have Classical with Gregorian as a sub-genre that's the same thing as having Gregorian as a top-level genre. Same with OP's problem with "World Music" genre (except for the culturally insulting aspect of it).
The only time it could possibly matter is if the system doesn't have sub-genres... but that would be a pretty ridiculous system.
Really genres suck for a different reason, because they are vague and overlapping and subjective. What I want is a composable classification system with actual objective traits about the music... so I can say "female lead singer, german language, trumpets, beats-per-minute 80-120" and so forth. I don't know if such music exists, but I would listen to it if I could find it.
edit: didn't realize the Songza doesn't have any sub-genres of Classical, so include it as a "pretty ridiculous system".