WAR design was flawed in the beginning. Or rather, I should say that the differentiation philosophy between the tanks was flawed.
The WAR needs to be able to MT, which means content had to be balanced to make it's "lower defense" shortcoming not a shortcoming, which meant that the PLD's superior defense was not needed, resulting in the PLD not being a tank with superior defense, but just a tank with bad dps. Tank differentiation should never have been about survivability and dps. It should have been about playstyle and lore. All tanks should bring similar utility and dps to the raid. But they should play wildly different.
The PLD was the simple tank, sword and board, passive mitigation. The WAR could have been an active mitigation tank (instead of the original concept of damage absorption). The DRK could have been a stance dance gameplay (as in actually frequently changing stances, not the current stance dance we know now).