I think the dev team needs to have a clear vision on the central concept for each tank. That's not something that should change from expansion to expansion, even if the gameplay does. It's also not something that should overlap with other tanks.

While DRK should have really been built around lifesteal from the ground up, it isn't. And rather than giving every tank their own token lifesteal move and diluting the concept, they should just double down and focus on building WAR up around that concept. Living Dead, likewise, makes no sense on a tank without focused self-healing potential. So put it on WAR and let them fight for their lives. They're the only ones capable of doing it.

Likewise, the most unique element of DRK gameplay that's persisted to date is TBN. That barrier shield concept is something that should be exclusive to DRK. Turn Shake it Off into something healing and HP boosting, and turn Dark Missionary into a groupwide bubble. Let us be the Zarya to their Roadhog. Bubble yourself, bubble your team, hit harder and faster. You could even tie Darkside uptime into it. Every time one of your bubbles take damage, your Darkside timer increases incrementally. While Darkside is active, you have increased damage and the old Blood Weapon style attack speed boost. Give Darkside the Greased Lightning treatment. Give us a shield styled invuln - when you hit 1 HP, any additional damage you take gets converted into barrier shields when the effect ends. The instant you start giving everyone their own personal watered down version of a "bubble", then you kill off the identity.

The dev team is too reactive. They're too busy putting out fires and trying to fend off complaints. The problem with tanking job identities is that there's no clear vision. So you could get a really cool ability that seems job defining, only for everyone else to get a copycat ability the next expansion. Or worse, it gets converted to a role action in a diluted form. You need to have distinct gameplay experiences that are capable of achieving similar goals. But the starting point is not to give everyone equivalent actions from a common template (Rampart/Sentinal/Hallowed Ground). The starting point is to develop unique concepts and try to solve the same problem different ways.