I think that the story is really important however the music is just as important. It's really difficult to seperate the two. I am a great Bowie fan and without the guitar of Mick Ronson a some of the effect would be lost.
The guitar playing of Marc Bolan was nothing to write home about but the lyrics of his early songs match beautifully. What about the wildness of Black Sabbath or the simplicity of some of the great blues players.
It's an interesting thought but I'm not sure that there is an answer its a bit like the old nature/nurture discussion.
At the end of the day it's what does it for you!