Honestly, this was a major problem for ALL 4e campaign settings. I mean, just look at what it did to poor old Forgotten Realms. Even in the case of Eberron, where I’m convinced the 4e cosmology got allot of it’s inspiration from, they still somehow managed to fuck up the cosmology by adding a 14th outer plane (if you know anything about eberron, you know that the numbers 3, 12, and 13 have special symbolic significance to the setting, adding breaking the pattern messes up a lot of the established symmetry existing).
I’m not really sure WHY wizards of the coast wanted all their settings to look like re-skinned versions of each-other in 4e, as it seems like it trades a lot of what made the settings unique and interesting (and thus individually marketable) for… what exactly? the ability to have crossovers?