An editor is to an author what a producer is to a musician - and like books, what consumers often think is good songwriting is actually good production. The same is true for authors.
The second thing to remember is that for independent writers good editors are hard to come by; scammers and incompetents abound. Worse, an author's editor has to be somebody who can tell the wordsmith "this sucks" in a way that will both get the point across and not make the author want to give up - and this is not easy. Again, that big author-ego comes with a price tag.
- Eric Plume