Just spitballing, but quite possibly because of contractual obligations that restrict fan input on the Realms, or that Greenwood isn't listening and has final say, etc.
In many ways, it might have been better for the game (but not the D&D brand as a whole) to have come up with a new setting without the baggage, and then have novelists write for it... kind of like what Sweatpea did for the (supposedly rather lame) movies. (On the other hand, Ken Whitman once mentioned that Courtney is in fact a gamer.)
Oh, and someone leaked a link to a playtest copy of the Epics module; it appears that the Epics modules will shape the "future" of the setting involved for their AL seasons.
Which tends to indicate that, from a certain point of view, Organized Play is becoming the way that the future of the setting is being influenced by gamers. (Note: A former WotC parter, AEG, has been doing this for their flagship game for a decade: L5R CCG... the winner of the big tournament helps determine the nature of the changes based upon a combination of their deck in finals and how it plays out. But they weren't the first, either.)