Our values change with every expansion. This doesn't have anything to do with playing optimally or your time commitment to the game.
Heavensward DRK was a fantastic job, for Heavensward. When you take an action like Plunge, for example, people loved it in Heavensward because it was the only tank gap closer at the time. It also showed up at a point where the broader playerbase was just starting to realize that you could negate a knockback with a well timed gap closer. Sure, you could negate it with Tempered or Holmgang, but Plunge was the stylish way to do it. In Stormblood, it was a liability. It was vastly inferior to Onslaught, which had a longer range, a faster animation, and could essentially be used on demand, and was coupled with the fact that IR negated knockbacks, and Holmgang also negated knockbacks. Stormblood also brought in faster and more frequent knockbacks than we had seen in the likes of, say, Midas. Plunge didn't change. The game did.
I think the interaction between MP and blood in Stormblood was an interesting idea. Dual resource systems are generally fun. The devs flirted with the idea of creating this blue-black deck style design where you burn MP to gain blood and burn blood to gain MP in an infinite resources loop that wins you the game. They did it for AoE and people loved how broken it was. TBN to gain blood, Quietus to gain MP, and so on. But they didn't dare to do it for single target, which is where DRK ended up being seriously disadvantaged. Bloodspiller actually never generated resources, and with very good reason.
You talked about the blood gain on Salted Earth. That's a nice idea, but it's very hard to balance AoE vs. single target. Either you'll generate too much blood in AoE, or too little in single target. The same was true for Blood Price. I think it's better to opt for a versatile kit that is balanced around both, rather than having something that's exclusively strong in AoE ('the dungeon tank').
I think it would be reasonable to change Abyssal Drain such that it's balanced around both single target and AoE. But to do that, you'd need to have fairly significant diminishing returns in AoE to keep it appropriately powerful in single target.
I don't see what Living Dead's problems have anything to do with coding. It's just a badly designed action all around. The actual invuln effect is not the problem. It's mathematically inferior to Holmgang even before you take the penalty into account. And the penalty itself is poorly executed, relies entirely on another player to understand how your actions work, has incorrect tooltips, and has no UI support to show how much healing will remove the effect. It'll be even better next expansion when your shield healer is struggling to cleanse it.
Stormblood didn't streamline Heavensward's kit. It ripped out large chunks of it and donated inferior versions as role actions shared across all tanks. It locked actions like Blood Price behind Grit such that you were denied access to them. It was conditional and clunky. It was widely regarded as the worst tank by a large margin for that expansion, and we're still recovering from the aftermath of it. Stormblood DRK was a terrible job, for Stormblood. Context matters.