I have loved pretty much everything about the Great Wheel cosmology since I first sat down with the 1st edition Manual of the Planes and read it cover to cover. When they added to it with Planescape (added, not replaced) I fell in love with all over again. It felt and feels like the sort of thing centuries of loremasters and sages would come up with as a sort of "grand unified theory". The biggest problem I had with the 4th ed version was that everything about it was designed to be super playable on the tabletop, with little concern for the worlds that supposedly believed in it. It felt completely artificial to me, and thus I see it as gamey and poor worldbuilding. On the other hand, the Feywild/Shadowfell dichotomy is workable and capable of being added to the Wheel without replacing anything (as 5th ed demonstrated), so that's all right.
Funny, I had the exact opposite reaction. The Great Wheel feels like a dreary mess to me--a hodgepodge of unrelated planar concepts, crudely jammed into 17 slots dictated by the D&D alignment system, its contradictions and inconsistencies papered over with ad hoc solutions. It's the Forgotten Realms of cosmologies. (In case it wasn't clear, I don't like FR either.)
The World Axis cosmology of 4E, on the other hand, feels elegant, cohesive, and evocative. The designers started with "order versus chaos" as their organizing principle, and layered on the "war between pantheons" that shows up in many real-world mythologies (titans vs. Olympian gods, Marduk vs. Tiamat, Aesir vs. Vanir) to create the Dawn War. The rest of the cosmology flows naturally from this, with the Astral Sea and the Elemental Chaos embodying souls/order and matter/chaos respectively.
The gods are concerned with morality, so we have astral dominions embodying various forms of good and evil and points between. The primordials care nothing for morality, so the Elemental Chaos has no equivalent--except the vortex of cosmic annihilation that is the Abyss. Finally, we have the Material Plane existing at the boundary between soul and matter. Its parallel planes, the Feywild and the Shadowfell, reflect a smaller secondary "cosmic conflict" based on life and death. Since that conflict depends on the union of soul with matter, it only exists in the Material Plane and its reflections.
One of the great tragedies of 4E was that a lot of truly fantastic worldbuilding got hooked up to a system that treated worldbuilding as mere decoration for a tactical skirmish game. And when the player base rejected the system, the worldbuilding was discarded along with it. I'd lay down a
lot of money to get a full 5E treatment of the 4E cosmology.
