The graphics (cover art, liner notes, disc surface) for a cd is often made available with downloads, so the design efforts would not be superfluous. In fact, the cover art is the usual means of displaying the song and the cd it came from on a download site.

I don't personally download much, but I know people who ONLY download. I did all the graphics for all three ShoreGrass cds and made them available as physical albums, digital albums and individual download mp3's. But then I'm a retired techie who enjoys the process as well as revels in new technology. Usually.

This is a very common issue today: printed directories vs online searchable databases, physical cds vs downloadable mp3's, books vs kindle readers, Newspapers vs websites, etc. Me, I want it all.