SE must be drunk.

[Sweetgrass]

Turning Parry into a passive mitigation stat is the only way they could make it useful without making it into the horrorshow that was Vengeance in WoW. Just have it as a +Defense/MagDefense stat so that it's somewhat useful instead of changing how it works.

[DaulBan]

snip

I agree that parry would be best as a simplified + DEF/MDEF thing on gear. I understand SE's wish to add a tank-specific substat, even if it doesn't really mesh with maximizing damage as a tank (whether or not tanks should shoot for high DPS is neither here nor there as far as I care). If it at least provided bonus defensive stats it could make tanking out of stance a bit easier/nicer on the healers.

A possibility could be renaming 'Parry' as 'Threat' and making it so that with more parry you generate more enmity, which would make maintaining enmity out of stance easier, but that could have some awkward anti-synergy if your MT has relatively low parry but your OT does, leading to issues around tank swaps. Maybe parry reduces friendly enmity by a % for non-tanks?