I don't see why Ten and Piety can't be the stat to stack, rather than Crit.

One of the issues I see with Enix's tank/heal design is they seem to be of the mindset that simplifying tanks/heals and trying to put as little burden on them as possible is the way to go. The result is a role that hits like a wet noodle, is dull to play and that doesn't feel like it has much impact on the fight. If instead, tanks/heals hit quite hard, had an engaging toolkit and were easy to pick-up but had depth and the tools to pull off some impressive saves in the hands of a great player, that would be far more enticing to pick up. I'd much rather pick up a potential juggernaut than a blue noodle dps that doesn't need effort.

Ten and Piety are part of this mindset. They don't have any real impact. They don't have good damage. They don't want you to need to stack them. They're just lukewarm, bland and simple like the rest of the role.