Here's my opinion on the Def/HP matters.
First, I'm indifferent to the order of the tank class defenses as long as we all balance out to have roughly the same defensive capabilities when considering all defensive stats (Def, HP, Parry, Dodge) together.
Taking Defense as it is, I feel there is not enough room to grow for 30 more levels. With +0 Osiris gear, average 16% blueseeds and Vit Def bonuses, I am already at 66% and 75% unbuffed in Bear and Grizzly forms respectively. I'm not even at my full potential in terms of runes, VIP, and external buffs. We're already nearing plateau of the diminishing returns formula so next tier gear will need to have jacked up stats to compensate in order for noticeable differences. Let's not forget that newer gear tiers would likely catch non-tank classes up in terms of Defense which reduces the gap between non-tank and tank classes and diminishing our usefulness.
In terms of class bonus, I feel that 15 HP per Vit should be the BM bonus, which means that other classes will have their HP bonus lowered (somewhere between 6 and 15 HP per point). Yes this looks like a nerf to everyone at first, but consider some of the following.
1. Everyone had only 6 HP per Vit before, and surviving raids was still possible with proper preparation and active healers. The AOV patch created a huge leap in defensive capability for all classes which renders early content useless. Lowering the HP per Vit for all classes will still allow them to survive content without being over-buffed. We're not supposed to solo things in game, but some people seem to be forgetting this. Unfortunately, the introduction of penetration stats shows that the developers are still in favour of buffing everyone and works against this path.
2. A lower HP pool means Potions will heal more in terms of a percentage of total HP. It makes crafted potions more relevant. Additionally, it makes the Healing bonus from Vit more relevant to all classes, thus making Vit a more desirable stat build for those who want to beef up their characters more.
2. If Vit Defense bonus is removed with the current gear set, BMs will still have 50% and 60% Def in Bear and Grizzly respectively. Still good defensively, still have capacity for future content growth.
I know my views aren't popular, but I prefer to look for big picture and am willing to take a short term loss in favour of it.