The difference and the problem with Azerite system is that in Legion you had clear goals to look at, but in BfA it's all too uncertain.
Let me explain:
- Artifact Weapons had fixed traits.
- You had to farm AP to eventually unlock those traits.
- The goal was clear: "if I unlock these traits I get more powerful".
- It had the disadvantage that you had to level several weapons.
Now with the Necklace in BfA:
- You only have to level one item.
- The goal is uncertain: "if I level this item I get... ¿¿??"
- You get item with random traits: that means you can get "better" item with worse traits, so the "better" item it's actually not that good (even sometimes is a downgrade)
- You are constantly farming to unlock the same traits. How much times do you find that you "cant" equip a new piece because you cant unlock all the traits and that means losing power?
- All that plus most of the time you cant actually know what traits are better (and how much) without sim it, because they're too vaguely described or they're too complicated.