Think of it this way: RBN isn't primarily an outlet for musicians to post their own music. Think of it as an alternate way Harmonix can earn money; musicians happily chart their own songs and upload them to RBN, Harmonix gets a good chunk of the sales, musicians become a bit more famous and earn some money, everyone's happy. If songs are free, this would prove to be of absolutely no benefit to Harmonix.
But $1 isn't much. Don't buy what you don't like is all.