The problem is that, especially given how extensible Jenkins is, accounting for all possible failures is impossible. So some will show the angry Jenkins error page.
Note also that this page is way more helpful to many users (and the developers handling the error report later) than a nice, but uninformative "an error occurred that we assume is vague related to authentication" page could ever be.
I'm currently working on improving that page (e.g. actually link to the wiki page explaining how to report issues and how the Jenkins project uses Jira), and will incorporate a simpler error message in addition to the full stack trace. It would probably look like one of the following in your case:
Failed to retrieve user information for jusurb; nested exception is javax.naming.PartialResultException [Root exception is javax.naming.CommunicationException: my.domainserver.xx:389 [Root exception is java.net.ConnectException: Connection refused]]
Failed to retrieve user information for jusurb; nested exception is [Root exception is: my.domainserver.xx:389 [Root exception is: Connection refused]]
While still not ideal, it's clear from either that it's a network connection issue involving your AD server, and the user jusurb.