Based on what I read above, I'll restate the question,

Why do the songs of Madonna or Ice-T sell a bazillion records, while the music of great quality that WE enjoy and understand doesn't. John McCutcheon criss crosses the nation and still plays in church basements. Even if you take the view that digustibus non disputandem est, you can still argue that from a point of view of quality, beauty, resonance with the human condition etc, Mr. McCutcheon's music compares favorably with anything, yet his doesn't sell. Why?

In a word Fashion (a form of ugliness so offensive it must be changed every 6 months -- Oscar Wilde, or as I call it mass conformity masquerading as identity). The clothing of past ages is no less beautiful, or more ugly than todays clothing, yet few are running around in Ascots and hoop skirts, or dressing up like Jackie Kennedy. Yet now we have body piercing and tatoos, where did that come from? No one knows. Cultures have been doing it for millenia, but why it should re-emerge in our culture now?

Tell me how to predict and explain the ebb and flow of fashion and together we'll get rich.