There are hundreds of thousands of people who heard that song, like that type of music, and would consider attending a show and spending real money to get in. They might buy a tshirt too. Pandora could notify listeners when the shows come up, and help bands plan their tours to towns with more fans.
It could be real revenue for the bands, and for Pandora.
EDIT: Doesn't even mean a UI change, could be done with ad retargeting, or any performance marketing mechanism.