The versatility of the classes stems almost entirely from their optimization for PVP content. As such every DPS class needs some survival abilities and every support class needs some DPS capability. Jobs can of course capitalize on this versatility but not by much, the traits of a class can have a fairly significant impact on what roles it can fill (particularly traits that enhance certain skills, IE Enhanced Outmaneuver) and right now there are no additional job traits nor can we select any cross-class traits.

As for keeping RDM in melee without focusing on DPS, my answer was to tie strong debuffs to their En-spells (so that they have to keep hitting the mob to apply the effect). Actually, my build has gone through some revisions trying to incorporate other ideas and I might repost it (or go back and edit it but it's unlikely anyone would see it as it is buried somewhere in the middle of the thread).