I think they have shaved down development cycles to the point where they plan and align them with financal goals (earning calls) in their company structure and the release has to be exactly then and there. You could splendidly see how they had fully commited to the azerite stuff in every aspect of the game and when they finally realized it wouldn't work out there were stuck with it. That was what gave us some hasty class overhauls in the last couple of weeks of beta, beause it became finally clear that random garbage procs are just no replacement for artefact weapons, tier sets and legendary slots. I think the whole overhaul and now the essence system is all just a symptom of these rigid dev cycles that neccessitate that you have to work on every actual change way before in the background, which is why we won't see actual changes before the next expansion.
It is the same with the new system. The essence system is still just glofied trinket slots, something they could have also done with azerite pieces, the main issue with them was the constant hunt for a decent piece of high level and good traits (most traits have no reason to exist tbh) while you constantly had to re-earn the actual trait unlock. None of that was neccesary for azerite pieces either, they just didn't do these simple changes before 8.2 which seems mostly stuborn to me.
Frankly I fear they still don't get why people didn't like the system. Like back in beta when everyone with a bit of logical comprehension could see how this would never truly work out like all the removed legion systems, it seems Blizzard is just flat out incapable of realizing it or their goals for the game are so far off from what the playerbase wants that they only dare to bedgrudingly admit it years later, like recently with the over-pruning of classes and the fact that removing things instead of gaining things with rising levels is just bad form in a (pseudo) RPG.