This migjht not be a very popular suggestion, but here it goes. I think if a writer wants lots of toolbars, formating options and the cluttered interface that inevitably comes with that, the writer would be much happier with MS word or Google docs. One of the main appeals of Butterdocs (and other similarly writer-focused apps) is being powerful yet simple, clean, non distracting. Keep it that way!
So here is my suggestion: add as little stuff as possible in terms of formatting for the editor and add ways to customize the appearence of a document when you export it. I think Ulysses does that.