I'm A Banana
Potassium-Rich
That's true of any setting. Campaign settings aren't there because they are "better" than homebrew games. They are there because the DM doesn't have the time, inclination or talent to build a homebrew to the level the campaign setting has.
Nor would I expect it to be better. But different. I would expect any campaign setting to give me a reason to keep playing it beyond "it's easier."
From what I can tell, FR, GH, and DL (not to mention some of the other 2e settings) all do that, to a certain degree. Anyone can run an adventure about ancient lost treasures beneath a desert, true. But FR has an entire metaplot constructed around those ruins in the desert. It has extraplanar beings of wierdness infesting the corners of lost worlds. It has the rescources, as a setting, to deal with the consequences of hidden secrets of ancient origin being brought to modern light. You explore some desert ruins, and it means something different in FR than it means in almost any other setting. If I wanted to play on extraplanar beings of wierd magic coming to light with the disturbing of ancient remains deep below the earth in a climate of often-open hostility between nations, FR offers me that in a way that it would be hard to just cherry-pick from. That is FR's hook, that is part of what differentiates an FR game from any other D&D game.
Similarly, if I wanted to play on heroics, world-spanning saviors, and planet-uniting events in an atmosphere of recent great accomplishments on a planetary scale, DL offers me that in a way that the other settings don't. And in a way that makes it different from playing a homebrew.
Eberron doesn't seem to offer me, at the moment, anything to sell it. It doesn't seem to have a hook, something that makes it different from playing a normal D&D game. It tries to cultivate an atmosphere of action-adventure whizz-bang kitchen-sink amazement, but the methods it uses to do that fall a bit flat (action points, fer instance). FR gives me a reason to want to run an FR game as opposed to a homebrew. I don't see any reason to run an Eberron game instead of a homebrew.
A campaign setting, IMHO, should offer me something different. I don't need a place to set my homebrew. I need something new, something different, something inspiring. Eberron, I think, certainly has that potential. It just hasn't been using it very well.