As I too often fall on the wrong side of serious-silly norms, I’d like to better understand what makes music fun vs. serious.   From What Every First-Year College Student Needs to Know About Washington:

Don’t dance at indie-rock shows. Maybe where you come from, dancing is acceptable or even fun. Not here. Music is serious, and being serious about music is serious, too. Seriously? Yes. You can smile in an ironic way. Or sneer. But keep those dancing shoes in the closet. You’ve entered folded-arms territory.

From the Sept. 8 New Yorker:

The modern classical-music performance, as audiences have come to know it and sometimes to love it, adheres to a fairly rigid format. … Before 1900 concerts assumed a quite different form. … The opera served mainly as a playground for the aristocracy. The nobles often possessed considerable musical knowledge, but they refrained from paying overt attention to what the musicians were doing.  Indeed, silent listening in the modern sense was deemed déclassé.  Johnson quotes a nobleman writing, "There is nothing so damnable as listening to a work like a street merchant or some provincial just off the boat." … Public concerts … [were] eclectic affairs at which all kinds of music were played before audiences that seldom sat still or quieted down. …

What changed? …. With the aristocracy declining … the bourgeoisie increasingly took control of musical life. … Programs favored composers of the past over those of the present, popular fare was banished, program notes provided orientation to the uninitiated, and the practice of milling about, talking, and applauding during the music subsided.  … By applauding here and not applauding there, the bourgeois were signalling their membership in a social and cultural élite. As Johnson points out, they felt obliged to reconfirm that status from year to year, since, unlike the aristocrats of yore, they lived in fear of going back down the ladder … Attending concerts became a kind of performance in itself, a dance of decorum.

There are important clues in here somewhere, if only I could understand them.

Added 17Sep:  Fortune has a nice quote about serious jazz in the comments.