This is partly why a bunch of us are waiting, because Azerite Armor bonuses could be why some of these changes came down the pipeline, as we don't have anywhere near the full picture yet. Sometimes changes filter in for stuff that's yet to be added, but makes the changes understandable. Also, it's a feature that affects every class, so they want to make sure the system is working right first, then they'll probably move on to Azerite ability balance/power (which they probably have already started with their internal testing), and then it'll show up on the alpha test realms when they have an acceptable test build of said powers.
Now, some changes I'm still trying to figure out, like the increase in mana cost of Hibernate. Best case, PvP reasons? Certainly not PvE, as I've used the ability once during testing... and it was mostly just to mess around while being Feral with a weird pull. Still don't want to aggro mobs if it's used on an out-of-combat creature, that's a change I think would be worthwhile.
The increase in cast time of Rebirth I kind of understand, especially if Blizz is trying to slow things down. However, I think it should be a change made across the board for all classes, or the change is likely dumb. Hurts Guardians/Ferals more than Resto/Moonkin honestly, although I haven't popped on the alpha since the change to see if it's across all specs or just the caster specs.