HP != Mitigation. As you add HP to a tank, if you don't equally increase the healers ability to heal that gain in HP then it means nothing, hence why Defiance was changed to give an increase in HP AND incoming healing to bring it in line with base Shield Oath instead of its orignal Wrath stacks giving healing bonus making Defiance half a tank stance.
Paladin was the required main tank for all of coil. Groups would run PLD/WAR, PLD/PLD, or even just PLD and drop the WAR for a DPS. Now that the lines are more blurred and you can bring any tank composition you want Paladins are going to whine till they are the best of the best again? I was forced to PLD for a very long time, and now, I don't even plan on taking it to 60 and pray that I don't because I've always found it boring. World first A2S had a Paladin in the group, there are still plenty of Paladins out there and plenty of groups that bring Paladin. My Savage group's other tank is leveling PLD so he can DRK/PLD if needed at the request of the group leader.
I can agree with an enmity increase for Paladin since the original intention of RoH having a lower coefficient was that they had to spam it even if they were off-tanking which, if Butcher Block and RoH were equal would result in the Paladin taking aggro, but now with Royal Authority there is no reason for them to not be equal.
I can't see a reason to buff anything else. Regardless of what people say Paladin still has the best physical mitigation of the three tanks, and yes right now there are a few magic mechanics that don't favor Paladin's CD options, but A2S is a perfect Paladin fight. Having a shield alone is ~10% overall physical mitigation and that's passive. People also seem to down play Hallowed Ground which is the most amazing cooldown in the game sooooooo many mechanics have been cheated/skipped by using Hallowed Ground.