Disagree, in this video you can see for yourself how the damage mitigation for PLD vs WAR is:
https://www.youtube.com/watch?v=xuSEqjWfGFc
I took much more damage than Shinzee did, bearing in mind he always had more/stronger mobs on him than I did. This is where one of PLDs underrated strengths comes in to play. PLD taking by far the least damage in most encounters, allows others to do more damage, ie: healers. You may also notice that I spent quite a large time in Deliverance in that video, purely because Shinzee's mitigation was strong enough to tank so much at once, which enabled me to DPS more. Even at the end of my video he deliberately takes mobs off me to allow me to change stance and push the phase, whereas I guarantee I would have required much more healing attention had I been the one to take from him.
PLD is great, and is always relevant, since it brings a lot of strengths to groups that can't be measured in simple DPS numbers, as mentioned above. It'll always be the lowest DPS as MT, but since it's such a potent "safe" tank, it can effectively increase the groups performance.