Far too many people equate complexity and challenge.

HW DRK wasn't engaging because it was complex. It was engaging because it was a fast, uptime-focused job. Hit stuff as it comes off cooldown, keep scourge running, and keep your MP in an appropriate range. Simple enough. But it was the fights and the mechanics that kept it exciting and fresh. It doesn't take much to create a mechanical skill differential.

The Stormblood iteration was more 'complex'. You had the unnecessary addition of a second resource meter to manage. There were different potency trade-offs between blood and MP. You had more unnecessarily forced double weaves. Yet it was widely disliked. At the end of the day, it was slower, more clunky, and more ineffectual. And worst of all, it just wasn't fun.

What I want to play is a tank that is just purely uptime focused. Stay glued to the boss. Use movement tools (gap closer/gap extender/blink) to dance from target to target. Baseline haste with high APM. Minimal burst, maximum sustain, every GCD counts. Pretty much any degree of challenge that you want should just come naturally out of fight design.

Defensively, I want revenge procs and design that rewards a thorough knowledge of the boss' damage patterns. That knowledge is one of the few things that differentiates tank gameplay from melee dps. I also want cooldown management to be a thing again, and I think the best solution is to just remove invulns from the game. It's pretty much the best way to fix Living Dead.