So the consensus seems to be that Ninjas can be tanks but they probably shouldn't be tanks and that Red Mage has been completely forgotten.

Maybe we can get the thread back on topic by discussing whether or not Red Mage can and should be a tank.

Personally I don't care much either way. I believe that Red Mage very well could be a tank job. In XI I once spent 30 minutes meat-tanking an IT troll with my RDM just to prove I could, that really has no bearing on XIV, but it solidifies my perspective of RDM being a durable job.

In XIV RDM could be an MP tank, consuming MP to defend against attacks. Either actively (through casting defensive buffs) or passively (perhaps via a mana shield ability taking damage recieved as mp damage).