Why can't they release two level 60 dungeons every patch (at least until/if the level cap increases) and have simply a Level 60 Roulette? Put them all in there. Eventually there would be more than the four we have now. Leave the Level 50 Roulette as-is. Leave the Leveling Roulette as-is. Finally, use the quest sync feature and put all dungeons into the EX Roulette but have them sync up to level 60. Could possibly supplement this with a few special rare drops or mobs, chance for a Mistbreak item etc. Something. This way running an EX you could literally get anything.