I would say that, given the way I prefer to play, my preference is for one-shot campaign worlds.
First of all, I like variety. I'm running an Eberron version of the Savage Tide adventure path now, but when that's finished I'm very likely to move on to, say, the Rise of the Runelords Adventure Path in Paizo Publishing's own setting, or convert it to a setting of my own design, or do a shorter series of adventures (either published or of my own design) - and that's if the next game I run is even Dungeons & Dragons. It's more likely to be something from the World of Darkness.
Second, my taste for variety extends to the people I play with. I wouldn't like to play multiple games with the exact same group of players - I like to bring different people into the mix. Now, my wife is likely to be involved in most, if not all, of the games which I run, but that's a special case. Other people, though? I just don't necessarily want the same blend of personalities around my table all the time . . .
. . . and the relevance here is that I'm not sure it's valuable to have an ongoing world in which all my campaigns are run, if part of each successive group isn't able to appreciate the continuity between campaigns. Doubly so if part of the group is, and exclaim in delight whenever they encounter something familiar, because I can't see where explaining exactly why it's so cool to run into X or Y again would add to the new players' enjoyment of the game. Some people may enjoy it, in the new player's place, but I'm not one of those people and so I'm not likely to make it a feature of my GMing.
Third, as far as I'm concerned part of the point of using a published setting is to allow those who are familiar with it to get "into" the setting using their knowledge. I'd rather play an Eberron game than a Forgotten Realms game not just because I prefer Eberron's approach to fantasy, but also because, as a fan of Eberron, I know so much about the setting that any PC I create is going to be truly rooted in the world.
This is important because I would never want to run a game where the PCs were unable to affect the status quo. If they want to, say, expose Queen Aurala of Aundair as secretly planning to resume the Last War, and cause her to lose the throne, then I want to run a game where that is possible - rather than a game where I have to keep her in place by fiat so that the setting isn't "disrupted".
The tension between the familiarity of a published setting and the need for PC freedom is something which I resolve by not carrying over consequences of that magnitude - so even if I ran another game in Eberron, Aurala would still be on the throne of Aundair, because the disruption her replacement would cause to the setting - while cool as the consequences of PC actions within the boundaries of a single campaign - damages the familiarity new players have with the setting, and mitigates one of the benefits of using a published setting at all.