I have to wonder whether or not it is an intentional strategy to keep public discussion of the Common Core ELA standards off the standards themselves. First we had everyone discussing whether or not there would be a required reading list when there never is in a standards document. Now it is all "percentage of fiction vs. non-fiction." That also is not determined by the standards.
In particular, if we have an over-emphasis on fiction, I've seen no evidence that this is directly attributable to current ELA standards, particularly at the secondary level. If kids aren't reading enough non-fiction in history class, the idea that this is directly attributable to the current ELA standards, and will be fixed by the new ones, is a joke.
And the main reason that writing assessments over-emphasize nebulous personal essay topics is not because the testing companies are run by hippies. It is because you can't assess a student's writing if they don't know the answer to the question posed by the prompt. This is not a philosophical problem, it is a practical limit in standardized testing.