Great rational for the Wheel.
In a schematic map configured by alignment relationships, the alignment planes look like a Wheel of islands. But when traveling by spelljammer each of the islands might be anywhere.
The Astral Plane is a realm of thought. Spacial relationships depend on concept. So concepts that associate with each other closely have islands that are nearby each other. Unrelated concepts are far away from each other. Also, by organizing the concepts by different a different criterion in a different context, means the apparent locations of the islands are in different locations. Astral islands arent always in the same place. Traveling the Astral Plane is more like traveling the stream of consciousness of a person. (The DM can have fun with this.)
The magic of the spelljammer helm helps automate the navigation the strange distances of the Astral Plane, whose mappings would change fluidly. But I still give players a sense of how things work in the Astral realm of ideals.
The dominions of an alignment can appear as islands that are separate from each other. For example, the Chaotic Good plane of Arborea might have the summit of Mount Olympus as a free-floating island, but the elven forest of Arvandor is entirely somewhere else in the Astral Sea. Arvandor might be in a cluster of Astral Sea islands relating to Elves, Fairies, and other Fey themes. But somewhere else, Mount Olympus is part of a cluster of islands relating to the ancient Greek-speaking world between the fantasy versions of the rise of Alexander the Great and the rise of the Roman Empire, with Egyptian-esque alchemists and theurgists along the way. Even so, whirlpools will show up to other Astral locations because of concepts that two places share in common, including a whirlpool forming somewhere to link Mount Olympus and Arvandor together because they share the concept of Chaotic Good ethics in common.
The map of the Astral Sea islands looks like results of a search engine query. Each island has a number of "tags" relating to its prominent concepts, paradigms and ideals. A cluster of islands can appear together that share a particular tag in common. The actual locations of islands change depending on which search criterion one employs.
Later at a different time, it is also possible to find a cluster of the alignment islands organizing together by the criterion of alignment, so all the Good islands locate above and all the Evil islands locate below. Then it actually does look like a Great Wheel, very much like the way the schematic drawing map depicts them.
Notably, different campaign settings − Eberron, World Axis, Dragonlance, Ravnica, and so on − can experience the Astral Sea differently. Because different worldview assumptions are in play, different islands appear. The Astral Plane for one culture can be completely different from the Astral Plane of an other culture. So reallife cultural sensitivities are easy for the DM to finetune − and navigate literally. Also, players can travel from one campaign setting like Ravnica to an other campaign setting like Dragonlance by means of the Astral Sea by finding islands with thematically associated whirlpools to the alternate locale, or by finding the wildspaces of those locales.
If I hadnt already decided many years ago that most of the Outer Planes are actual worlds infused with divine power floating in space, I would definitely use this/your concept.
It almost makes me regret (this is a compliment).
You can do both. Your conceptual locales exist somewhere scattered across the outer space of the Material Plane. When traveling the Astral Sea by spelljammer, players can encounter these locales as large and small "wild spaces" rather than as islands. There can be an Astral cluster of both islands and wild spaces together locating next to each other thematically.