What would a new tank even contribute at this point

[UkcsAlias]

What did Gunbreaker and Dark knight bring? Damage. To make up for their weaker defensives and utility. But apparently we can't even have that. So what's the point of these tanks? Are they going to turn them even more into Warrior clones in the next expansion just to be safe? What would be the point of a new tank? What will be the point of any complexity? Where would a new tank fit in, in a role where 1 job, and the simplest one at that, does everything and is the best at everything? I'm going over every piece of content right now, and i find it hard to justify playing anything over Warrior. Normal content, extremes, savage or even ultimates. Warrior is the best solution to every problem. Why can't different tanks be good at different things? Was Warrior doing 3% less damage really that big of an issue when it already has so much going? I Just don't really see the point in having multiple different tanks anymore.

The problem is fight design. There are very good offtank mechanics, but a lot of fights never utilize these:
- Splitting enemies (force the tanks to pull them apart)
- Double tank busters (and yes, some can be taken by a well shielded dps, but convenience makes a tank prefered)
- Adds, idealy with an instant aggression towards the off tank (so the main tank cannot instantly provoke them).

Even for normal mode trials/raids tank swapping should become a mechanic:
Each 'special' attack (diffirently marked tank buster) adds a stack to a tank. Upon reaching x stacks, the affected tank will get ability blocked (while death can be punishing, losing control is equaly anoying. So silencing/hyseria/stuns all work). The stacks deplete over time (60s). This means that if a maintank disagrees and instantly takes it over, they will cause their own issues.
For these mechanics, you can also make shirking become stronger bassed on debuff stacks (making the maintank also capable of shirking the aggro away, but the offtank unable to instantly shirk it back). If a tank died, and the maintank gets disabled by this, aggro would still at least be effective for a while until the other tank provokes.

I think this would be at the same difficulty level as most healer checks, and with a very clear effect also turn into mussle memory quickly.