I think if Wizards actually put some focus on Eberron lot's of people would actually like it. Unfortunately they aren't really worried about the RPG and instead have their sights set on something bigger and they believe FR will get them there.
I don't think its as much FR is the their ticket to something bigger as much as its really the setting of least resistance.
* Dark Sun, Ravenloft, and Planescape are all "nontraditional" fantasy settings and don't represent the "typical" D&D experience.
* Dragonlance and Eberron are closer, having been home to either successful novels or video games, but have nonstandard elements and tweaks that change the assumptions of the core game.
* Greyhawk and Mystara are both "generic", but suffer from being barely-detailed skeletons of a setting that are better known for their iconic adventures than anything about the world itself.
* Nentir Vale has every problem GH/Mystara has, plus its stymied for being conceived of in 4e.
* Forgotten Realms is richly detailed, home to several successful novel series and video games, and doesn't violate or require parts of the Core Rules to be changed in order to play.
So Forgotten Realms has all the advantages of Dragonlance and Eberron (success in other media) and Greyhawk and Mystara (generic, core rules based setting) and few if any of any of their disadvantages. From a branding standpoint, its a no-brainer. A gamer can get into the setting via multiple avenues (gaming, novels, video games, or the upcoming movie) and get a detailed, if generic, experience. It's harder to do if, say, Eberron is the MMO setting, Dragonlance is the movie setting, and the current AP is in Dark Sun; people will wonder why my mmo PC is an artificer, the movie had kender (which aren't in the PHB) and the module I just bought is happening in a giant desert with stone weapons.
I can't honestly fault WotC for making FR leader of the pack, but I still hope we get some other pack members as well.