Tier added flavour, but with that added restrictions.
Legion having tier pieces beyond the bonus requirements was for the reason of not having a tier set bonus conflict with legendaries.
Getting tier should have been something to feel good about, but as soon as it matched the slot of a legendary that you wanted to use, it became trash.
Arguably with legendaries removed, the remaining fixed slots could have a tier set shaped around those.
But then there is I think the risk of those tier items becoming the entirety of your BiS list.
Upgrade forging takes away from I think the typical BiS list, something I personally feel is utterly boring.
That anything which isn't on that list is simply considered bad.
Not being able to simply dismiss even the entire loot of a boss I think adds value and importance to content otherwise ignored.
And we are still being told there is "nothing to do", despite a wider variety of content than ever still potentially offering something than it simply not.