Man, I see a lot of people complain about DRK, but I don't see much actually wrong with it.
- Spamming dark arts is the lore/story of the job. I guess you missed that leveling up. This isn't objectively a bad design.
- Very little self heal/dps gain. Wrong. Highest HPS tank on the charts right now is DRK. Oh look, highest DPS tank is DRK as well.
- Living dead does its job just fine. Have you tried combining it with Sole Survivor for that 30% max HP heal + MP? Then throwing Blackest Night up with that MP?
- Everything costs insane amount of MP... again, part of the lore. You "attune with the darkness within you"... you don't use a bit of MP, you go balls deep.
- Blackest night costs a lot of MP and its "nice"... you're just repeating yourself now. Shielding yourself for 20% max HP (or a party member 10%) every 15 seconds is great. No other tank can do this.
Clearly, you don't like the job, but that doesn't make it bad, never mind the worst. DRK is about pouring everything you've got in to that next move, but being flexible with what that next move is, not have to build up a burst window and wait around for the next 2 minutes (looking at you WAR). The way they can convert resources (blood/mp/healing/shielding) gives them an interesting play style, and gives tons of flexibility, especially in AOE situations. I know rigid static raid teams aren't going to appreciate flexibility much, but it is well designed and does a great job.