Usability guidelines say hyperlinks should be underlined to provide users with a visual clue that text can be clicked on to navigate to another part of a document or to another document.  This is of course important for digital versions of documents (odp, pdf), less so (if not at all) for hardcopy versions.

Unfortunately Impress does not underline hypertext links nor does it provide a way to globally style text links.  The link color can be changed by using LibreOffice's setting "Tools -> Options -> Appearence -> Unvisited / Visited Links.  But there is no way to underline all links without manually changing each one, a tedious task in the age of css and styles!

Writer provides a specific style for hypertext links, "Internet Link", internally called "Internet_20_link".  Unfortunately, this text style is not available in Impress.  I would like to see it added (actually Impress style management should be brought up to the level of writer in general, but this is the use case that most specifically impacts me).