Why Avoid Parry?

[Ralvenom]

then how can you possibly argue that the Slaying tank will tend to play better than the Fending tank?

It's simple. The full slaying tank knows his choices are 1) don't use CDs as often and die OR 2) use CDs often, live, & do damage. When you have less room for error (because you don't have a larger HP pool to fall back on), you're forced to play tighter.

Also, most full Fending tanks tend to require more healing.

Btw, it's worth noting that both myself & dank1 used the word "tends", as in "to be disposed or inclined in action, operation, or effect to do something". So, before you (or anyone else) decides to jump in & go, "But I'm a full Fending tank who uses all his CDs, so I basically take no damage"...remember exceptions to the rules don't make the rules invalid.

Also, think about that concept a bit: a full fending tank who uses all of his/her CDs. As much as you (and others) may dislike it, if you used your CDs all the time AND were in full (or mostly) Slaying gear, how much more damage would you be contributing to the party. I feel it's VERY selfish in this game to NOT contribute as much damage as possible to the party, which means gearing in a manner that ups your damage is key, especially when we have enough CDs to make it such that Fending gear is NOT required in the current meta. I honestly hope this changes slightly in 3.2, because it would be cool to have a few fights where I have to a beefy tank. But, this is still 3.1, so suck it up & contribute as much as possible to the party already.

Increased output = increased enmity, increased hp recovery from moves such as Bloodbath

It's worth noting that increased HP recovery from Bloodbath = increased emnity (~10%+ emnity), so you might as well use this as often as it's up on pulls.

Unfortunately, PLD only has Circle of Scorn to act as an AoE damage dealing emnity generator. (Flash doesn't deal damage, so...using Bloodbath & Flash together is generally not great.) So, it's still kind of weak for PLD, but it's better than nothing. WAR & DRK have enough AoE emnity generation to get significant gains from Bloodbath.