I've been thinking about this reply a lot and it's interesting in how it interacts with my day job, which involves a lot of technical writing.

In writing there are always spots that are rougher than others and I suppose that as in art, part of mastery is in learning to both recognize those spots and know how to fix them. A large difference is that if a spot is left rough in writing, it's usually a matter of priority or deadlines. It's very interesting to me that roughness can be intentional, either as a deliberate stopping point, or as you point out, as technique for contrast.

Which isn't to say that all good writing is infinitely smoothed. In the same way that you've seen art lose its spontaneity, I've seen overly polished writing lose its life too and either become plodding or soulless.