If Paladin is "specialized in defense" shouldn't its defense be better always?

[Phoenicia]

Every Shield Swipe proc is a delay in GCD, can be a DPS increase or decrease depending if you spread your combo on several targets or if you have the time to finish your combo.
Every Stun can be a bit too late if the casting bar is short and your GCD is on.
Every stance change is a reset to your combo, meaning that your DoT and RoH will fall.
You need to think your cooldown rotation to match the frequence of tank busters so that you'll have one ready each time.
You'll need to follow the pattern of attacks to cast Clemency (even as a main tank) without being interrupted.

I would agree with you if any of these scenarios were relevant or vital to your survival. They also have the following misconceptions:
- Doing your three combos, your GB and RoH are actually clipped by at least 1 GCD before they fall off. So you can Shield Swipe or change stances with a benefiting impact on DoT/Debuff timers.
- Since when was your stun relevant to raids? You can't bring something as irrelevant as this. And when your stun DOES work, it's 6s of 100% mitigation (similar to Hallowed Ground!!!). It is the longest stun in the game! Can be repeated with a DR for a total of 10s of stunned target!!
- Stance change is 1 GCD, plenty of time to refresh DoT/Debuff.
- WAR and DRK also have to consider their CD rotations as well. It's not just IB.
- You are not a self-healing tank, you are a pure mitigation tank. If you do manage to cast Clemency, you become ahead of WAR in terms of damage mitigated and healed. So I do not see the minus in here.

Are we grasping at straws here? I mean really?

As for Dark Arts, it costs a lot of MP. Would you use it on each Dark Passenger, each Dark Mind, each Soul Eater and some Power Slash ? Or even with Adyssal Drain ? Do you need Carve and Spit to gain MP or do damage ?
Grit prevents you from using Blood Weapon, Darkside is needed to use several skills, and Soul Eater only heals you with Grit. You have plenty of things to think about if you want to max out DRK.
In fact, I'm pretty sure very few people had already managed to "perfect" DRK's gameplay.

Again, none of these impact your defensively. The core mechanic of DRK is that you have only so much MP to use Dark Arts 4 or 5 times a minute. WAR can't even have enough Wrath/Abandon for 5 skills a minute! You choose which skills to boost based on situations. 9/10 times you will unload DAs for more DPS. What you are talking about is just integrating Dark Arts into the basic skills to achieve "perfect" DRK gameplay. Again, are you grasping at straws to make DRK sound difficult?

Sorry, but stance dancing on WAR is still the more forgiving, just because it converts Wrath to Abandon and back, meaning you can prepare your damage in tank stance, and strike immediatly in DPS stance.

So WAR losing Inner Beast is forgiving when the other two tanks keep all their defensive toolkit. It is also forgiving because it is the only one that locks you out for 10 seconds. Please.

It converting Wrath/Abandon is just a side effect. DRK keeps the rest of its MP when it turns on Grit and loses no MP when it turns it off. Why should WAR lose all its resources? It's already paying for the stance change by losing access to abilities and getting locked out for 10s.

Yes, WAR's previous entire toolkit was far too behind. No mitigation skill, no oh-shit button and a tank stance which was massively behind the PLD.

I haven't done T5 as a WAR, but I suppose people didn't expect tank swaps, so WAR was in a really bad spot. With Vengeance and tank swapping (On top of Stoneskin and Adloquium), I'm sure it would have been perfectly viable.

You do know Vengeance reducing damage by 30% was a 2.1 thing, right? Before 2.1 it was almost impossible for WAR to solo tank T5. But it was done with swaps. ShinRa (my FC at the time and Phoenix Server first T5) did T5 with swaps even after 2.1 came out.

WAR became the "better" solo tank for almost any encounter after 2.1.

Yes, "proactive vs reactive" is a personal opinion. It's just that WAR had Thrill Of Battle from the start, and Defiance is clearly a reactive skill, so I think it'd a more "coherent" toolkit.
And you'd still keep Vengeance and Raw Intuitionn which are proactive.

Thrill of Battle is meant to be used proactively before you receive the damage. It gives a 20% of your max HP as a buffer. Using it as a reactive heal is the wrong way to do it.

Defiance is useless if you're not at max HP or aren't receiving the heal. It has a more proactive nature than reactive.

Only reactive ability in the old WAR toolkit was Inner Beast which you used after big bursts to refill HP faster.