I agree with some of that. Wolcen studio took PoE's approach to unique items, but they should have taken more from Diablo 3 i.m.o. Having uniques as the undisputed best items would mean that every character's gear slots would ideally be equipped with uniques and only uniques, which would make customised legendary items obsolete and no longer worth crafting. That would also not be good for the game, but uniques as they are at the moment are a bit underwhelming.
They should consider making uniques' affixes scalable like all other items, instead of static. That, in addition to an "upgrade unique item level" city project would mean that we could choose a unique or two to create a build around, and always have their strength up to par by using the new project (with the uniques' ilevel upgrade capped according to our character level or maximum expedition level unlocked).

Yes, Unique items are not that unique right now. Only some seem cool like turning Staff Basic attacks into spell damage (even though Basic attack is mostly useless later on).

Some Unique shields allow you to cast Sacred spells. That's different.

Some of Uniques like Edict Dagger is just very underwhelming. No sockets. Nothing special. Dagger already has access to Poison damage. If anything, a Staff with high Poison damage is more unique for Annihilation toxic beam build because there is no +Spell damage for Toxic.