Lines with multiple asterisks mean something different from outlines marked with spaces and asterisks (or hyphens, or numbers). You can only put a TODO, a priority, or a tag on a line with multiple asterisks. The spaces-plus-whatever lines are not meant for top-level tasks, but for little sublists.

I'm inclined to agree that it's a bit unsightly, but the font-lock hack works well enough for me, and I use the distinction in my outlines all the time.