SAMURAI SHOWDOWN

[Khalithar]

Even if you went with a mage tank, it complicates itemization.

This is patently untrue. In other games where they have tanks that wear leather or cloth, they simply have passive buffs (think shield oath/defiance/grit style) that bring their hp/armor levels up to par to the appropriate point and make certain defensive moves scale off their primary stats. They don't actually have to change itemization, at all. If you're worried about avoidance stats of which this game only has the one of (parry) then they can simply make the stat something like "mage armor: increases armor by X%, increases HP by Y%, and increases parry by Z% (based off intelligence)."

Edit: Found a good example of one of my favorite mage tanks, the Arbiter in Rift. I forget the exact level but shortly in the tree they get an ability called Arcane Ward that functions like the tank stances in this game, here's what it does, "enables Block. Causes Block to derive from the Mage's Intelligence. Increases Base Health by 25%, Resistances by 35%, and Armor by 150%. Increases threat generation by 300%. Reduces damage and healing done by 20%. " They could very easily add a buff like this without changing current itemization.