For the last part: also Warrior, pre-Deliverance, and Paladin's Sword Oath probably would have been the same if only jobs were able to give traits, sad as that may be.
On the whole, agreed, though giving every tank some form of % vulnerability infliction seems every bit as uncreative or blatant. (Easy enough to vary up though, of course.) One thing I would personally like to see is just a lot more ability for a tank to support tankishly even when not the direct target of enemy attacks, such as through interception, staggering (damage causing suppression), and through debuffs that unlock certain similar mechanics for one's party. For instance, I've especially been looking into how I can create a Shield Oath that can be sort of a tank/utility stance that doesn't actually require you to be MT to still have a hell of an effect (or in this case, toolkit, mostly). And then there's that toss-word I've been throwing out on every thread looking for mechanics suggestions, progressive AoEs, wherein just about everything is at least partially interceptable.
I suggested an enmity revision before that would have the indirect result of increasing dps on tanked targets, by drawing the enemy's focus focus away from other attackers to reduce the active and/or passive defenses of the enemy against them. Though this would work between dps as well, especially with skillful enmity splitting and target swapping, it's easier and has a greater maximum effect with a tank. Another was Stagger, damage-based suppression (with an additional modifier, much like enmity now but tied more with what you'd expect from one's animations than just their role), which worked both for sabatoge-based mitigation (which DPS roles would be more greatly expected to coordinate into) and offense through that suppression of enemy defenses as well. Since tanks would have some of the highest Stagger modifiers, this would also mean some of the highest indirect damage contributions. The aim was for those systems to fit what we're actually seeing on screen, to make our animations feel like they have realistic weight and intuitive effects. But hey, would something like that also do what your looking for?