If you're a rock star whose defining work came out somewhere between the years of 1969 and 1994, chances are your body and soul have atrophied into tiny prunes thanks to a decades-long carousel of hedonism.
Creating anything is hit and miss -- for every amazing work, that same artist likely has ten pieces of crap that they'd happily see blasted into the Sun.
Very few fictional characters are pulled from thin air, because what's the point of having friends and family if you can't steal their essence and sell it to strangers for entertainment?