It doesn't really have to be very elaborate or technically complex. It just needs to be engaging. Reaper is an entirely resource driven job with a burst window that that is resource gated, not time gated. The burst window itself transforms your actions into new ones, with a 1.5s GCD for players who enjoy a bit of button mashing. It's even got the most interesting gap closer.

Think about what it would be like if you had DRK designed that way. Build up blood gauge to enter Delirium every 60 seconds, complete with that shadowy-flame effect that players have been asking for since Heavensward. Transform your base combo into upgraded actions with a super short GCD. Maybe they hit multiple times and restore MP. Maybe your character's base movement speed is faster with it up. Every second Delirium window, Living Shadow splinters off of you and does whatever actions you did during the last Delirium window. Finish with something flashy, where you and your shadow(s) hit the target multiple times to end the window.

The whole point of resource driven jobs is to build up gauge to do something fun. That's what makes them more entertaining than your standard 44-step fixed rotation job. Nobody cares about how mathematically complex your spreadsheet-designed job is when they're busy mashing skills out at triple the APM.

There's also something joyful about having movement skills that you can just use when you feel like it. Imagine if DRK had something like a personal only Lost Impetus (complete with a shadowy speed boost) as our own Chi Torpedo. These sorts of abilities are great to use in fights. But perhaps more importantly, they're fun to use all the time. Do you think that you're going to see Reapers just walking around the map? Or are they going to be blinking all around the place?

I would have thought that the need for engaging and fun gameplay would be obvious to the game designers who actually play their own game™. But then again, these are the same people who designed Living Dead, so they're clearly not playing DRK.