I think most of the settings from those days are pretty well tied into the aesthetics of the era they were produced in. Forgotten Realms was slow-grown from the days of D&D becoming what it was, which is why it serves as a “generic” setting for the game like Greyhawk.
Wizards has only released two major settings in the last two decades: Eberron and Ravnica. Eberron was a product of its time, the early 2000’s. You can call Ravnica a slight cheat, but I think the fact that the design process crosses between the Magic people and the D&D people makes sense after a certain point.
I think- no, I think I’ve read- that Planescape was influenced by White Wolf and their faction-heavy games of that era. Sigil being a hole? Probably a mix of the grim and trying to explain why the world is the way it is backward from what came before. You can design a setting around Sigil, and it looks quite a bit different (Sig: Manual of the Primes).