The current user profile exposes a limited set of information. If an admin wants to extend the XWikiUsers class with additional fields like "interests", "hobbies", "favorite books", etc. he also needs to edit by hand the XWiki.XWikiUserProfileSheet page and write custom code to display each of his new fields.
An idea is to add a new section in Administration where an admin can configure which fields of the XWikiUsers class to display. He still has to add the fields to the class the old way, but at least he doesn`t need to write any code because the class editor is good enough.