So we have a new expansion and the tank balance we were promised in lieu of a 4th tanking job is nowhere to be seen. I'd like to talk about why and what can be done, and its really very very simple.
PLD got more utility. Yes it already had utility. BUT, DRK and WAR's utilities were either DPS oriented (Eye) and thus more valued, or had higher uptime or were more easily implemented/applicable to the content (Path, Reprisal, Delirium).
In 4.0, DRK and WAR were pretty well cleaned out. Both of them lost numerous abilities and PLD lost none. Even now, PLD has about the same amount of button bloat if not more than it did before. Most of this loss was felt in the utility department.
Make no mistake, the new abilities and additions to PLD were well deserved. However SE did go a little bit overboard with the potency buffs (Fast Blade buffed to 160 potency - wat).
See, the thing that made DRK and WAR so much better in 3.x was that their utility was better AND their DPS was better.
Now, you've got the reverse of that problem. DRK and WAR lost all or almost all of their utility. Which would have been fine if their DPS had stayed where it was relative to PLD. But it didn't. PLD now deals just as much if not slightly more damage than DRK and WAR. Now, this DPS disparity is very small, but when you consider the fact that they pruned almost all of the other tanks' utilities, you can see the problem right?
DRK and WAR either need utility to make them competitive with PLD, or they need to have their damage buffed to compensate.
"BUT SYZ! THEN WE'LL GO BACK TO 3.X and PLD WILL BE BAD WAHHH"
-NO. Because Path/Reprisal/Delirium and WAR's exclusive provision of the slashing debuff are no more. Even if DRK and WAR both outdps PLD by a noticeable margin, when raid mitigation is required, they have next to nothing to offer anymore. And before you say raid mitigation isn't valued, realize that after Gordias, these were the main reasons DRK/WAR were taken over PLD. DPS checks in Midas/Creator were not harsh at all. Reprisal/Path was just better.
Right now, the only thing stopping groups from going double PLD is the LB penalty. They'll take a DRK if they feel they need TBN for whatever reason, and WAR if they're more concerned about DPS. I'm not even saying this from a meta standpoint - wouldn't YOU take double PLD if you were serious about clearing content in a timely fashion?
To all PLDs still recovering from 3.x, this is not personal; most of us wanted PLD to be buffed, and frankly, PLD's DPS was barely behind the others at all as of 3.5. Had they removed Path and Reprisal things would have been relatively balanced in terms of utility vs. DPS between the 3 jobs. And because none of the tanks has a DPS utility like a trick attack or the like, its even easier to balance. Give the tanks that offer less utility more DPS, not the same or lower. No one wants PLD to be left behind again, but now once again, you have one tank that is doing things the others can't, and everything they can do it can do just as well if not better. DRK and WAR offer NO raid mitigation whatsoever. TBN helps one person at a time, but its nothing compared to Cover+Intervention+Divine Veil. And they don't even offer substantially higher DPS to compensate for this. This is a problem.
SE, please get it right and stop bouncing from one extreme to the other.