Mercule said:
The Great Wheel isn't a sacred cow. Planar travel has become somewhat key to D&D, but the specific layout of those planes isn't a big deal. To be totally honest, I think every setting should have its own cosmology and set of planes. The Great Wheel is Greyhawk's. Eberron has its own, as do the Realms (though they were once said to share one with Greyhawk).
First, the Great Wheel is considered by some, including the OP, as being just as key to D&D's unique 30 year history as the crunchy elements of the PHB classes and races. It may not be a Sacred Cow to you, but to those of us who have used it extensively, it is one. The Great Wheel is Greyhawk's, true, but it is also every other setting's before Eberron.
Forgotten Realms ret-conned their cosmology after 3.0 was already out, so the 'once said' comment you make is not acurate. You make it sound like the Realms never stated it either way and that they were just shoe-horned into the Great Wheel. It was explicit in any book dealing with FR gods. For example: Faiths & Avatars (2E FR God Book) shows the plane/domain name for each FR god, including dead ones. Turning to a random god entry: 'Amaunator (DEAD): Domain Name: Mechanus/Keep of the Eternal Sun.' Just because they chose to ignore or change the printed history of the setting in 3.0 does not mean that they only hinted at a Realms/Great Wheel connection. It is right there in black and white.
Mercule said:
Dark Sun was explicitly set in a different multiverse, attempts to retcon it into working with Planescape or Spelljammer not withstanding.
Dark Sun was never retconned into the Great Wheel. It was there all along, with the understanding that it was virtually impossible to access the sphere of Athas becuase of the Grey.
Mercule said:
Dragonlance wasn't as explicit, but wasn't particularly warm to the concept.
Dragonlance used the Great Wheel, though the average scholar from Krynn didn't have the 'facts' about the cosmology correct. The Gods all had domains within the Great Wheel, just like the Realms gods did. The setting wasn't 'warm to the concept' of the Great Wheel because it just didn't focus on the planar aspect of D&D. Thats not what the setting was about.
Mercule said:
Lack of cosmologies for settings like Birthright is far from the same thing as implicit use of the Great Wheel. It's just that -- a lack of definition.
I'll simply state that the above statement is misinformed. From 'The Book of Priestcraft' for the Birthright setting I'll again choose a random god. Page 17:
Haelyn
Lord of Noble War, Lawmaker, Patron of Anuire
Greater Power of Mount Celestia, LG....
...Domain Name: Honor's Glory/
Mount Celestia...
Birthright did not suffer from a lacking cosmology or a 'lack of definition'. The inhabitants of the setting were simply too busy dealing with mortal affairs to worry much about the planes. The planes were there whether they cared about them or not.
Mercule said:
Really, the Great Wheel was very characteristic of earlier editions. It was exclusionary and defined by exception. New rules had to be created for every new idea. I really hope this is an indication that the 4E developers are attacking that "manage by exception" concept and that it carries over to other aspects of design.
This statement I will agree with. I too hope that the exceptions are just that 'exceptions' and not the rule.