And if you do, you know there actually is a rule.
If it sounds good, put your finger there.
+1 and very well articulated, there
is a rule.
If this rule didn't exist, we wouldn't have music.
Consider this spectrum: painful noise, sound, mediocre music, good music, great music. (With great music spanning generations and centuries.)
With absolutely no rules you get noise, that few if any, will be interested in listening to. An example: Record a chimpanzee banging on a grand piano, and then try to have Pandora or your local radio station play it for the masses. I don't think you'd get too far.
Why is Beethoven, Mozart and others still reverred today? I'd say because they understood the rules and applied them masterfully. And these rules could very well be psychological or emotional.
If we drill a bit deeper we find that proper rhythm is one element that plays a huge role in good and great music. I'm hoping that thru music theory I can discover other elements.