Holy trinity.. Or maybe not.

[JTribal]

Reasonable Explanation

Yes, thank you for restoring my faith in humanity by providing a clear explanation. Although I'd be concerned about the usefulness of a Bard if this were to happen..

...What I want is for there not to be such an incredibly sharp divide between things that a melee dps can tank, and things that they can not....

To put it in even simpler terms, I want the relative strengths of the classes to be about the same in endgame as they were in the early game.
...The tank does almost as much damage, about 80-90%, as the dps when not in their tank stance. Later this drops to as low as 40%, which is where their current undesirable status comes from. I think 75% would be a good number. So if your average dps does, what, 400 dps in turn 8, your offtank, assuming they geared themselves like a DPS, would be doing 300 or even 350 should you choose to bring one instead of the roughly 250 they do now.

Basically, they need to put more of an emphasis on abilities than on stats.

Sorry, I'm still not understanding what you're getting at, your explanation is extremely contradictory. Do you want more support abilities or a buff in strength or tanks to be removed from the game or what?

Ever heard of a VIT dragoon? Me either

That's because Dragoons are not Tanks, same reason you've never heard of a VIT Summoner, Black Mage, or Monk.