the need for 3rd tank class

[Allyrion]

WoW Deathknights had CD rotation options... it didn't work- why rotate CDs when other tanks passively mitigate? They ended up redesigning them to make tanking easier.

Then they made all the tanks rotate CDs and you had an actually varied and interesting tank system.
With tanks that were more diverse in playstyle than the watered down dps in that game. And amazingly, all were about the same in terms of viability.

There are other ways to have creative tanking. But this game does follow the WoW model to some extent.
It should at least take what WoW did right.