Well, XEP-0045 v1.24 is the latest version and it was last updated in 2008, which is not to say that the listing items were actually changed in that version. Besides, it just seems logical that if you use affiliate with to display the members (which works in OpenFire, as well as ‘outcasts’), you should be able to do it with any of the other affiliation levels.
It’s handy to be able to look at the owner/admin list without having to type /config. Also, standard members could potentially have access to show the owner/admin list to, say, figure out who to talk to about some sort of administration issue.