So as someone who played FFXI I'm sure you are quite familiar that DPS could off-tank all the time and did so as the situation demanded, why would they add defensive cooldowns to DPS jobs if not to allow us to potentially stay in the fight until the tank could be raised and back up to fighting speed. Apparently the concept of skilled dynamic play is beyond your grasp, there is no need to stay to such a hard line of the "Holy Trinity" that people cannot help out in roles other than their primary one to salvage a fight gone wrong.