Yes, tier sets didn't offer choice, but when a new tier came out it was a brand new set with a brand new effect. If 8.2 launches with completely different traits that alter your playstyle in new ways, it will be great - but if season 3 is all just the same traits with higher ilvl, it will not feel as good. At least with legendaries once you had them, you had them.
I am mostly agreeing with you that azerite is better in the sense that you're not having to juggle around your gear as much to get the proper configuration. It was dumb that some classes had BiS legendaries taking the spot of a tier slot.