Hmm... This is interesting indeed, I think actually it would be practical if Paladin gained a trait that enhanced Aegis Boon to recover comparable MP to the HP is regenerates upon blocking and to, as you said before, enhance Outmaneuver's block rate and MP recovery.

Even still, I feel like Paladin was always meant to tank along side a Warrior, not exclusively. It's the 1-on-1 tank that can heal the other guy too, and was never meant to heal just himself. It's the pre-healer that uses his MP up at the start of a battle to ease the burdon of hate on the healer by healing the main tank. Holy Succor is a case in point imo. That's just what I'm beginning to think though, based on the job's blatent lack of real enmity tools.