Why Crit for tanks?

[Lynnreia]

intrinsically the less damage the tank takes, the less the healer has to heal, now do healers out dps tanks? probably not, but I'm sure they'd appreciate it. besides, I can heal myself.

this makes even more sense on trash mobs, because the pld can heal oneself, whereas the healer probably wants to enfeeble or aoe or something. Half the healers are probably just filling the role to get a dungeon spot and do not actually main heal, so once again, putting less weight on their shoulders makes sense.

Now IDK about you, I am not very far in the game, but I am experienced, I did play 1.0 and beta, I did master FFXI, I know my stuff.

With a full tenacity build I was able to solo T1-T5 completing all but T5 before level 62. I used dark knight for the kill but I used PLD/WAR frequently for the rest

My point is, in my scenario, I wouldn't have done it any other way. I geared for tenacity implictly, reaching practically 1000 ten at such a low level. This made my souleaters strong enough to outlast twintania's enrage. I'll delve into this deeper on a future note but my preference is, TEN > SKILL > DET > CRIT > DIRECT TMYK

Unfortunately, as logical as it might seem for a tank to take less damage to lessen the burden for the healers, it only really matters if you're doing lower level content with an inexperienced healer.

At higher levels, both tanks and healers have a multitude of available tools which makes healing a tank, that rotates cooldowns properly, into child's play. This is why CRIT > DHT > DET is the general go-to in higher level content, because there's nothing challenging the tanks and even if something did, the healers have an abundance of OGCDs to keep the healing up without needing to lose uptime on the boss/trash.

Basically, if you pick up TEN or DET, you will deal less damage and bore the healers even more than they already are.

Furthermore, at harder content like Savage and such, the deciding factor for defeating the encounter boils down to killing the boss before their enrage and the faster you can do so, the easier a time everyone will have, including the healers. Even on the most hard-hitting fights, I get by fine with the skills I have available, and even if a healer might have to GCD heal my co-tank, we both need to focus on damage to actually beat certain phases in time. I have seen plenty of 0.5% wipes and gearing defensively would only widen that gap.

So all in all, tanks and healers both have enough tools to keep tanks alive without TEN/DET, which is why extra damage in the form of exponentially scaling CRIT is preferred.