-sex appeal and/or "coolness" of the musician(s), fashionability
-public preconceptions, peer pressure, advertising
-availability, presence, marketing
All these things effect peoples' perceptions of music and their ability or inability to appreciate it.
A metaphor I liken this phenomenon to is Japanese food products.
If you've ever eaten at a Japanese restaurant or bought a Castella cake or even a roll of sushi you know how much attention they pay to the presentation of the food: putting things in neat wrappers and nice containers, usually symmetrical, often colorful and always clean.
The thinking is that your enjoyment of the presentation of the food will add to the overall pleasure of your eating experience, even if the food isn't all that good in the first place... And you know, it works! Presentation can turn simply passable food into a gourmet dining experience.