Roles for Samurai, Red Mage, Dancer

[Welsper59]

And I won't even start on how a caster tank just isn't feasible, even if it did physical damage with it's "spells".

While I agree about the points regarding SAM being a tank, I wanted to point out that caster tanking is absolutely a feasible thing. Mage tanking is almost as long of a tradition in RPGs (the general genre) as normal sword and board types. The most common form of mitigation for them is magic shields or barriers. If you ever played original Starcraft or Broodwars, think Archons in that example. A specific boss fight in the TBC expansion of WoW had the Mage class have to tank a boss as well, using the bosses shield against them. Sometimes magic manipulation itself becomes their mitigation, as is the case of Rune Fencer in FFXI. Though they use a 2h weapon in that game, the concept of runes to ward harm isn't exactly exclusive to people who would wield sluggish weaponry lol.