From Reading Like a Writer: A Guide for People Who Love Books and For Those Who Want to Write Them, by Francine Prose:
Among the questions that writers need to ask themselves in the process of revision — Is this the best word I can find? Is my meaning clear? Can a word or phrase be cut from this without sacrificing anything essential? — perhaps the most important question is: Is this grammatical? What’s strange is how many beginning writers seem to think that grammar is irrelevant, or that they are somehow above or beyond this subject more fit for a schoolchild than the future author of great literature. Or possibly they worry that they will be distracted from their focus on art if they permit themselves to be sidetracked by the dull requirements of English usage. But the truth is that grammar is always interesting, always useful. Mastering the logic of grammar contributes, in a mysterious way that again evokes some process of osmosis, to the logic of thought.