Alright let me argue this from a different perspective, because I actually really like clemency and agree that it's fine, it being a niche GCD option makes it good for solo duties or some progression situations, I can remember actually using clemency in hard content and casual content. That being said clemency shouldn't be taxed (like you wouldn't/Shouldn't tax vercure on RDM).
I do not agree with the statement that PLD's tanky enough a major issue with PLD's sustain is that the Paladin cannot choose when they wanna use their biggest burst sustain, as most of its tied to damage rotations, which isn't great for the job, I rather PLD get a OCD burst heal and reduce their magic rotational healing.
Intervention point is "ok", the issue is when it comes down to it Warrior for example has a effect that will heal both targets, Tanks such as gunbreaker and Dark knight have a lot more smaller mitigations such as Oblation or aurora along with another personal CD, so they can also help with double tank busters, it isn't really "paladin exclusive ability" to be useful on double tank busters when a dark knight could use dark mind and oblation on self then give TBN to the MT.
In summary PLD Issues are: Controlled sustain, lacks 2 Personals, has useless abilities such as "Cover", Blocking being Janky, depedent on auto attacks for personal cooldowns, DV being a worse shake it off and also being clunky, Passage of arms being too situational, Intervention actually just being a worser CD then all the other tank cds
The benefits of Paladin are pretty much a joke If you want a tank with sustain? go warrior, if you want a tank with mitigation? go dark knight, want a tank with a bit of both go gunbreaker, two of which also do more damage and all are way more simple to play.
I think they need to reduce req/confit healing and put that somewhere else giving PLD a OCD heal (Not replacing clemency, because its a good ability), would generally be a good step, fixing up cover and DV/Passage and making Holy shelltron less clunky would generally at least put PLD a bit more in line with other tanks.