This. The focus of the Nobel prize in Literature should be to highlight authors and poets who are masters at what they do, yet mostly unrecognized by the public in general.
When literature prizes like the Nobel, Man Booker, Hugo etc are handed out, the winning as well as nominated writers' works get highlighted. People who usually would never have even heard about these works become aware of them, read the synopsis online, and then perhaps even end up reading some of them.
Music icons, on the other hand, already get a lot of attention (and money).
It's not even as if he was an obscure name whose work has not been appreciated and enjoyed by millions.
Why Bob Dylan Shouldn’t Have Gotten a Nobel