> One possibility is that touring musicians lose touch with ordinary life, and therefore no longer create anything that people can relate to.

Reminds me of an article I read about R.E.M. around the turn of the millennium. The journalist notes that the band members (now all multi-millionaires) now spent their time moving from one posh luxury hotel or perfectly air-conditioned space to another around the world, living in an international cosmopolitan bubble even when not touring. This seemed the very antithesis of the struggle and feeling of local community from which several great rock subgenres had emerged, and it was no surprise that R.E.M.'s work had become bland.