TiamatShadowScale and MagiusNecros said all.
Again, it's not just about spq or raid mitigation, it's about fun.
The DRK's 70's gameplay is not even interresting as the lvl 60 of the WAR and the PLD...
War is a game about counting Fell Cleave with all other abilities to raise your dps and your beast gauge, Pld is a game about a magic burst phase, a physical burst phase and a dot gestion, since Drk is just spamming DASE, using a "Blood" buff + Délirium when it's up and using Bloodspiller asap.
And if you are OT, you don't even have to think about well placing DA, since the potency gain is 140 whatever the attack you use... Yay.

Oh, I think I'm becoming salty about the DRK's case...