See, I actually hated the fact that the World Axis was specifically designed to cater to adventuring. It felt very gamey to me, while the Great Wheel felt like something wizened sages who only kinda know what they're talking about would come up with, based on the information they had.
But my opinion on these things is well known.
For my part, the Great Wheel's "a place for everything and everything in its place" thing makes it much more gamey, despite being less adventureable. IRL cosmologies weren't clean, neat, and (most importantly here)
precisely comprehensive. The Norse had nine realms--about which very little was known. The Greeks knew the world was round by 500 BC, but had Ultima Thule with some
crazy stuff said about it, and (at least by the 2nd century AD) were comfortable with what we would call blatantly sci-fi elements (alien races living on the Moon and Sun, e.g. Lucian's satirical
True Story.)
As I see it, the World Axis isn't "made for play" (though that is the
Doylist reason it exists.) Instead, it represents Watsonian
imperfect knowledge. We know a bit about the Elemental Chaos...but who the frig knows what's beyond the edge of the parts people have seen? We know there's a "Feywild," but a fixed map thereof? Hilarious, pull the other one. The ignorance and incompleteness makes it natural--much more like real medieval maps (the
hic sunt dracones, or
leones if you prefer more historical prevalence.) To have an understanding as precise and comprehensive as the Great Wheel, where anyone with even a little education on the topic can know the precise layout and (in most cases) composition of literally every plane except the Abyss (since its structure is infinite layers and thus...can't be fully spelled out)...just feels really, really artificial. It feels much more like "I have to have all these planes existing, because the alignment grid
requires it." For all the complaints 4e got about "grid-filling" with its classes, the Great Wheel should really get some flak for grid-filling
planes.
If the Great Wheel were explicitly given as a best-fit approximation with either known exceptions, or outstanding questions left unanswered, it would feel a lot more like the best-effort
attempt to understand the cosmos, not a perfectly-comprehensive
atlas of the cosmos with no parts left out or unaccounted for.