You can find the evidence that most writers don't look closely enough at things in a lot of semipro publications, writer's workshops, and fanfiction archives. Lack of observation--really *looking* at things--will lead a writer to represent them by symbols. This goes for characters, bits of description, setting, character actions, you name it.
And I think that lack of realization that a writer needs to observe as acutely as a painter does is tied into the divorce of writing from other arts that truepenny mentions. I've learned a lot about writing from talking to painters and potters. Negative space, for example, and its uses. Accurate detail over symbolism. showing the
unique thing rather than the symbol for a thing.
For an original fiction writer working with original characters, making a realized character breathe. For a fanfiction writer (or somebody working on a media novel, or an homage, or a pastiche, or historical fiction, or--), presenting a version of the character that is recognizably a view of the original.
Anthony Burgess manages this with Kit Marlowe in A Dead Man In Deptford. He's not my Kit, mind you. But he's recognizably somebody who could have been somebody's impression of Kit Marlowe. Which made me very happy, even though I disagreed categorically with him about Kit.
But then, Burgess was always a bit of a Shakespeare worshipper, so I can't hold it against him too strongly.