Music and Worlds

There's an interesting episode on Imaginary World's Podcast titled   'Worldbuilding in Music.'  It's a short episode talking to the band Vertigo Drift.

It interested me because they talked about worlds and working with artists and writers to make their musical world larger and more diverse. It won't take you long to listen (18 minutes) and they talk about shared world building which has always interested me. Thieves' World did it, Tabletop RPGs do it all the time. Novels set in other peoples worlds or Intellctual Property.  Does it depend how much freedom an author has within the world? Aspirin and co had a pretty free rein, the Warhammer 40K novels a lot less so.

Shared worlds do you like them or loathe them?