It has been over a decade before Napster effectively ended copyright for recorded music. Music sales are down. But did copyright encourage creation of new music? Has the quantity of new music suffered on account of the effective elimination of copyright? We now have a detailed study. From the abstract:

In the decade since Napster, file-sharing has undermined the protection that copyright affords recorded music, reducing recorded music sales. What matters for consumers, however, is not sellers' revenue but the surplus they derive from new music. The legal monopoly created by copyright is justified by its encouragement of the creation of new works, but there is little evidence on this relationship...We assemble a novel dataset on the number of high quality works released annually, since 1960, derived from retrospective critical assessments of music such best-of-the-decade lists. This allows a comparison of the quantity of new albums since Napster to 1) its pre-Napster level, 2) pre-Napster trends, and 3) a possible control, the volume of new songs since the iTunes Music Store's revitalization of the single. We find no evidence that changes since Napster have affected the quantity of new recorded music or artists coming to market.