In today's expansion, players have access to the new trial of Rubicante. As typical for new extreme trials, it offers weapon drops for others. However, for most healers who don't have the 635 weapon, this weapon is essentially useless due to one reason: piety.
In fact, this entire tier has seen healer gear plagued by piety. Half of all healer gear available this tier has piety!
The problem is that piety is a worthless stat. All piety does is help improve MP regeneration. However, all healers have tools to help them restore MP that more than does the job. Healers also have numerous non-MP using skills to heal, to the point where the only time a healer needs to actually engage in using MP for healing is when someone else in the party messes up a mechanic and gets hit by something they could avoid.
If piety is going to remain a prevalent stat on healer gear, then it's time for the developers to fix the problem with how useless it is. To this end, I have two potential solutions to suggest:
1. Piety gives healers a small boost to their damage but provides less MP regeneration. This would make piety a lesser version of determination like tenacity for tanks, but would be more worthwhile since not affecting healing and giving less MP regeneration would let it improve damage more than tenacity does for tanks.
2. Alternatively if the developers don't want to see piety just been the healer version of tenacity, then give all healers a unique effect that piety influences. One issue I've seen healers have is that healing has gotten far too homogenized. There is less uniqueness between healer jobs now than ever before. One way this could be achieved is giving all healers a unique effect, and piety could be the source for affecting this unique effect. For those familiar with WoW, this would be something akin to the idea of mastery. To go a step forward, here are some examples of how this could operate in practice:
White Mage - Gives a chance on casting Afflatus Misery to be granted a Blood Lily.
Astrologian - Gives a chance per tick of Combust to consume Combust and deal all remaining damage when target with Combust stand within an Earthly Star.
Scholar - Gives a chance on casting Broil to trigger casting Ruin 2, though the MP cost of Ruin 2 is still consumed.
Sage - Gives a chance upon casting Toxikon to consume MP instead of the Addersting
Note how all of these effects are intended to deal damage so as to not upset the current healing meta. Also note how in most instances, the improvement to damage is at the cost of some MP. Since piety helps restore MP as well, this offsets things a bit. The exception to this was white mage, which of all healers gets the most use out of piety currently. These also aren't the only potential ideas and are meant to be examples.
Finally, if the developers don't intend to improve piety, then it's time for piety to be removed entirely.