mimic the most commonly used scheming for a style (ie, all the themes for style A use colored title backgrounds, while most of the themes for style B don't)

Is that why Basic Boxes is missing elements which are present in its default theme? Same question for Bases (and why the sidebar's on the left instead of on the right). I think I'd like it better if the theme matched the original designer's intentions.
Also it should be made clear that these --all previews actually but even more here since they're supposed to let you compare styles more easily-- are just one version of this style.