I love this suggestion.

Way I see it would be

Gla: Dark Knight, Paladin, (maybe Thief(Dual Wield daggers))
Pug: Monk DD, Monk Tank (maybe eva tank), Dancer even
Lancer: Tp builder spec with lance, Defence spec with short lance and shield.
Mrd: no idea. maybe viking/warrior. more increase att at loss of def abils
Arc: Sharpshooter (high power single shots), Ranger Varied debuffs and maybe even a companion

Con: Healer, Blm, RDM! (simply allow em to use weapons and en spells!
Thm: Scholar, Death mage

Obviously just some off the cuff ideas but the OP certainly has a point here.