IMHO, the questions about "When XYZ should be opened ?" are a bit tricky, the problematic thing is more about loot tables and itemization. I don't mind having Maraudon from the start, more dungeons is a better experience, but some items that drop there are too strong and make some loot in MC irrevelant. The T0.5 should be considered in that regard too. Maybe this gear should come later as a catch-up mechanic, but the dungeons should be there for the leveling experience.
I'm against balancing, AKA let's buff/nerf this spec to the ground, after 13 years of WoW existence I don't think it can be done. But let's say a few itemization here and there could make some okay-ish tanks and off-tanks druids: at least getting to the defense cap and an unmissable taunt/swipe bonus (maybe trading the Tx piece with an alternate Tx' with an agent of Cenarian Circle ?). I don't think paladin should get the treatment because the Alliance already have exclusive PVE perks.
Kind of reassuring all my big NOs are there at +90%, yeah I'm looking at you flying/LFD/LFR. For the rest of the survey, hypothetic future "classic" expansions should not be discussed this soon.