@jared:
I've got two points.
1. Hover isn't a thing we can rely on. Even desktop computers have touch screens now. 2.The colour red usually means that something's wrong (in our case: a page doesn't exist yet), and so does the "!" icon. "Dotted Underline" on the other hand has no meaning to it, it's super abstract. Users would have to learn what it means by trial and error.
-best, max @awesomephant