There is no reason Tenacity and Piety shouldn't be buffed. If it becomes the "must stack" secondary stat, how is that any different to Direct Hit or Crit? Better to be chasing a tank or healer specific stat as a tank or healer rather than avoiding it like the plague.

To become useful, both should have equal damage contribution to Direct Hit in addition to their current effect. Nothing more, nothing less. In this way, a Piety/Tenacity piece is your BiS, but a piece without it is still absolutely fine.

Tenacity pots are a nice idea, but personally I'd just make it a giant healing potion. 4 and a half minute cooldown and losing your dps pot is more than fair and it serves as an emergency option. Perhaps keep the vit for flavor and restore 80% health.

Also pots badly need to be allowed to weave properly. Why is this still a thing?