When I was in high school, I saw an oscilloscope rendition of musical notes. When notes are discordant, the oscilloscope shows a tangle of criss-crossing curves. These tangles represent the mad jangling of bouncing air molecules. These jangling air molecules then bombard the cilia of the inner air, irritating them and stressing the brain.

Is it any wonder that people everywhere like the orderly molecules of the I,IV and V chords? (I just watched a Jackie Chan movie, "Twin Dragons" where Beethoven's music was a central feature.)

But when things get more complicated, individual variation plays a role. I get very irritated by rock. Jazz puts me to sleep until they play a loud, discordant note. (This is equivalent to yelling at a person when your poetry put them to sleep.)

German folk music, no matter how sad, doesn't use any minor harmonies, or at least so I've read. There goes the idea that minor and sad are interlinked.

Just thinking thoughts at random, here...