DRK being compared to past FF games.

[Krr]

If you're implying that the hate generation on Souleater is a sign that it's a tanky job,

I'm implying that FFXI had a completely bonkers metagame and jobs were not "designed" to do anything but resemble classical Final Fantasy characters until very late into the game's lifecycle. The community chose DRK to be a high-risk high-reward DD, not the developers. Just like they chose NIN to be a tank and all the other ridiculous role assigments we've seen as the game evolved.

This is a bit of a stretch, as what creates the distinction between DRK and PLD Cecil is the fact that DRK Cecil has an offensive special command (Darkness), while PLD Cecil has a defensive special command (Cover).

That's true, but compare both versions of Cecil to other members of the party - both of them do less (but more consistent) damage with their attacks, have higher HP, better armor, and better defensive. Dark Knight Cecil was hardly a damage-dealing powerhouse in the face of what Yang, Edge, or the game's various mage characters could do. It's hardly a stretch of the imagination.

As for Gafgarion, he had the same stat, gear, and even attack skill progression as the other Knight classes in the game, which were front-line tanks.

Simply put, the idea that Dark Knights come into the party for their damage abilities and that their heavy armor and high HP aren't relevant is a community projection mixed with personal opinion, not the reality of the mechanics of any game they're in - except Final Fantasy XI, where NIN, MNK, and even THF had moments in the metagame where they were tanks. Beyond lifedrain and lifeburn, the relatively recent iterations of Dark Knight typically have a theme of abilities that maim, cripple, and otherwise debuff his enemies with Black Magic or similar 'dark forces', and I honestly don't doubt that we'll see a mechanic where they're empowered by taking damage from the enemies they're taking or placing themselves in other 'risky' scenarios.

And even then, there's nothing saying we can't have a lifeburn mechanic for OT DPS, so long as it's not something you can spam to the point of griefing your healers, or a couple of life-draining attacks, so long as they aren't the only way the class can defend itself.

Sure, thematically, Dark Knight is an offensive counterpart, and the other side to the Paladin's 'coin'. A mirror, however, is not wholly an opposite, and the two jobs have always had mechanical similarities that make both fill a role as heavy, frontline warriors.

Except in Final Fantasy XI which for some people 'round here may as well be the only Final Fantasy game, I guess.