This. The purpose of CoO is to level your 3rd class.
I agree...but was implemented poorly. If they really want to limit it to leveling your third class they should have had the requirement that one of your classes should be at 50 (number pulled out of...). As it is now, you get your toon to 20/20 then go to CoO to get one class to 50+ and only go to those other (very worthwhile zones imho) zones well, probably never. And people ask why the game seems empty...well it is, everywhere but Silverspring, CoO, Xaviera, and the new zones.