A Little Confused Over Uselessness of Unique Weapons

I get that rares play a big part in this game, and I get that Uniques are more of a "find these to maybe turn a build on for fun" kind of sprinkle in for loot. Some are incredibly powerful obviously, like the HH belt.

The part I don't understand is why the weapons are so useless.

Maybe this is unintentional, maybe it's an oversight or a bug I don't know. But the fact that the Unique weapons do not scale up with the item tiers just seems weird to me. If the Unique weapon could drop as a advanced/expert variant to have baseline stats in line with that content tier, it could at least be an option - as is, I am looting nothing but level 10 Unique Weapons in level 70 content.

It feels... odd.

Now, the reason I say maybe this is all unintentional, is for some reason the Unique staves I loot seem to have the proper ilvl spells attached to them, indicating they are scaling properly to the ilvl drops / content they are found in. I have a level 68 req Unique Ashen Staff I found with like a level 14 or 16 spell. Why these seem to be the only ones scaling, I'm not sure.

Either way, it just seems so strange to basically have zero viable options for Unique Weapons. Rares are cool, I'm fine working on rares, but that doesn't mean the possibility of a cool Unique Weapon for a build wouldn't be interesting.