Well purely from a student's perspective, I would want my ground instructor to be (i) doing it because he/she wants to and (ii) have some commercial experience to relate to.
Number (ii) is not essential, but does give extra weight/spice to the lectures. Most ground instructors are ex line/military pilots or navigators and can really teach from experience (Keith W and Alex W are very good examples).
I would certainly not want to be taught by an aspiring pilot who couldn't get a job and can't think of anything else to do.