Wagner in an essay on the “Outlines of the Artwork of the Future” argued that theatre (opera) was the most fully realised and free art as it combined all other arts. See the web site for Multimedia; From Wagner to Virtual Reality.
The essay is in Prose Works vol. 1. This has been reprinted by University of Nebraska Press in 1993. An excerpt can be found in the book Multimedia; From Wagner to Virtual Reality.
“This purpose of the Drama, is withal the only true artistic purpose that can ever be fully realised; whatsoever lies aloof from that, must necessarily lose itself in the sea of things indefinite, obscure, unfree. This purpose, however the separate art-branch will never reach alone, but only all together; and thefore the most universal is at like time the only real, free, the only unversally intelligble Art-work.” (p. 9)
Is there something superior to the more integrated arts like multimedia and opera? Or is it that more constraint there is, the more scope for imagination on the part of the reader/viewer?