I'm no expert here...
All I can give you are my opinions.
1. I like Eberron, I dont like FR. At the moment, FR has too much 'power.' FR is TOO well known. You can't do anything in it without upsetting someone who has memorized every little fact everywhere. Eberron is new. Eberron is full of politics, and no one yet knows where the story is headed. If I want to take my Diamond Throne campaign and drop into a fairly unexplored region of Eberron, I can. (In fact, that what I plan to do.)
2. I was not interested in Eberron when I first heard about it. I saw the campaign search (and I kick myself for not entering!), and when they annouced the winners, I looked to see. I got the pre-release pamphlet. The art looked interesting, but it looked disjointed. Then it came closer to time to release, and the hype started. I watched, I listened, I was not interested. It wasn't until I mentioned here that I was looking for a changeling for a PC that someone recommended I look into it. Then I went to work on a homebrew, and someone told me how the artificer would work well in it. So I started thumbing through the book to see. Every time I looked at it, I found more I liked, until I eventually ended up with a copy of my own and plenty of ideas on how to use it.
(Coincidentally, the same thing happened with Monte Cook's Arcana Unearthed.)
The only reason the hype and advertising and WOTC's 'push' to sell it worked on me is because it was always out there, I ignored it for a while, but eventually the book itself convinced me.
Now, I have never enjoyed forgotten realms. I have yet to read any DnD novel that was worth my time (there may be some out there, I dont claim to have read many of them). One of my players loves FR, but only the pre 3E stuff. He knows the setting frontwards and backwards. He runs awesome games, and I play in them, but only because its the only game in town when he's GM.
Eberron at least tries to tie most of everything that already out there into the setting. I can run an orc or hobgoblin campaign easily enough. No one is going to complain if I drop a mind flayer into an adventure. Then add on top of it all the political climate. I don't like p[olitics in the real world, but I love the intrigue that a good game sets up. Of course, politics IRL are rarely anything like a good game, but that's beside the point. I like the idea of a power group I can align myself with and not be 'lost in the crowd'.
FR, especially in the 3E days, has suffered from power creep. Interestingly enough, the RIFTS anaolgy works for me. I quit playing RIFTs for the very same reason. Why play a street rat when eveyone else is running around in glitter boys and SAMAS armor? Every new book added some new overpowered toy.
And as far as using the FR name recognition to sell books and video games? Yeah it may be true that more people recognize the FR logo these days. But guess what? When I see that logo on a game or book, I usually put it back on the shelf. 'Oh ANOTHER forgotten realms game. yuck.' Sometimes name recognition can have the opposite effect, and I really doubt that I am the only one who passes on FR materials. Selling Eberron is new, you dont have the legions of rabid fans worried about upsetting their favorite details, and my limited budget just might make room for a new setting over anything that came from Faerun.
One last thing, before you think Im just some 3E fanboy or a wet behind the ears newbie: I cut my teeth on the 1E books, the ones with two column small print on every page and the random dungeon tables in the back. Where it was a trial to get psionics, or become a monk. I have played many 2E games, including several in FR. I picked up 3E for a variety of reasons that have been thoroughly discussed elsewhere. My favorite settings previously were wierd settings (Spelljammer, Ravenloft), or full of politics (Birthright). With Monte Cooks Arcana Unearthed and Eberron, we now have new settings that aren't clones of other settings. I don't have to worry about Drizzt in funny clothes showing up, or Elminster, or any of the clones created by fans of FR who want to do the same thing.
Sorry for the length of this rant, Ill return you to your regularly scheduled web surfing now...