> Underlining doesn't make text look like a link. There are faces
> with the underline attribute put on text which is not a link.
> It would be confusing for users to think that such text is a link
> and try to click it after learning a new Emacs convention of
> underlining all mouse-1 sensitive areas.
> Also underlining often produces visual clutter, especially
> in buffers with high link density like dired, grep and compilation
Web page designers often use underline only for mouse over if they do not like underlined text. It is sometimes awful on web pages and sometimes instructive enough. Maybe that could be an alternative here, since the buffers have a fixed structure and if the underline is seen once when mouse is over them the user probably would think that clicking mouse-1 will follow the link?