Small PLD changes that may fix the class?

[Phoenicia]

Paladins could have -vastly- improved defenses and it wouldn't help their current predicament.

Exactly, any buff to paladins' defenses "make no difference" unless they defensiveness absolutely crushes the other tanks. I.e. Tank in sword oath and still take less damage than Grit/Defiance DRK or WAR.

Paladins' issues do not lie in their defenses (or lack of). Paladins' issues lie in inherent weaknesses that lead to more problems. Their weaker aggro leads to DPS loss. Their weaker DPS leads to unjustifiable increase in mitigation. And so on.

To "fix" paladins, they need to be either: "Absolute best defenders" so there is no environment where it wouldn't work, or fix their aggro so they can dish out more optimal DPS. Or make them much more viable as off-tanks.