Just because DRK's DPS is behind, even a bit, and doesn't offer anything unique doesn't mean it's so bad it's automatically carried. Believe it or not DRK can still contribute properly, and if you don't believe that then remember that a DRK was part of an Ultimate Bahamut clear. Yes that is a cliche defense but in this case an effective one as no doubt the entire group must contribute their all to clear it.