I'm definitely not an FR fan, so this will probably sound like heresy to some people.
I'm not sure that FR is a distinctly 'gaming' world, anymore. WotC is certainly making more money from the FR novels than the gaming material will ever generate (see above point about NYT Best-Sellers list). As such, I think FR is a great way to draw people into the hobby.
Lots of gamers got their start by reading Tolkien, Vance, Brooks, Jordan, Martin, etc. and wanting a bit more of that world. There's a desire to then play in that setting. The trouble is that IP is held pretty tight -- and, it often doesn't translate well to game rules.
FR provides a consistant, successful presence in the sci-fi section at the book store to draw people to the concept and the setting. I doubt you can read FR novels for long without discovering that it started (or shot to fame) as a D&D setting. Boom! Instant invitation to play. Of course, the source material needs to be able to support the people who are playing in the Realms because of the novels -- which may (data would be great) be more than the number of people playing in the Realms because they like D&D.
So, it almost seems that the Realms are a bridge brand to help introduce players to D&D. I actually appeciate FR in that regard.