I agree that the story and characters have their own life and it is discovery to write. This unfortunately doens't make it good in and of itself. Often it can lead to self indulgence. A good writer has at least some sense of his reader, and the ability to self edit to a degree, while writing. Unlike jazz, it is the rewriting where the magic comes together.
My main reason for not liking Jazz is that it seems self centered. Clearly the performer is enthralled with being a virtuoso and this leads to self indulgence, the artist assumes it is great because it keeps going. Similarly some writers confuse verbiage with quality. Thanks for a stimulating thread.