“For an artist, there's nothing better than having the opportunity to create a world that doesn't- but could- exist.”
― Christophe Lautrette
I guess this is the best definition of what production design is all about. That explains the fact that its not just visual - you have to be a writer, a poet, a historian, a researcher, an artist to love this challenge.
Those art forms have more in common then it seems. Its not about audio or visual or literature, its really about this universe that you create.