I raided with all three tanks in Stormblood, and exclusively played DRK up until Sigmascape launched. It was incredibly dull then. Now you have way more tools at your disposal. Abyssal Drain is something to use in raids now, Double Plunge, Living Shadow, Edge of Darkness, higher overall Black blood building (only gaining 10 per Souleater combo in Stormblood was pure ass when WAR gained what, 20? 30?). An actually fantastic burst window.

All this is much better, in my opinion, than just pressing one button between the same 3 GCDs