Right, the Nentir Vale/Dawn War cosmology is pretty cool, objectively. The problem is that they also made it and its tropes apply to older, established settings, resulting in changes that alienated some veteran fans. Which is why I wonder if things would have turned out better had they not done that, and instead made Nentir Vale core but just one of many supported cosmology options (like in 3E). Then, when the Realms returned in 4E, it could have continued to use either its own unique 3E cosmology, or gone back to the Great Wheel, and players would felt old and new were equally supported. Might not have made a difference for 4E's success, might have made a lot of difference.
It's kind of funny that the most successful current D&D thing, outside the game itself, is basically using the 4E cosmology. One would like to think it'd lead Wizards to give it a featured role again. (Unless, again, the "First World" is secretly just that...)