Why must we feel the need to bash campaign worlds at all?
Classic Greyhawk is one model of a campaign world. It is valid, it was tried, tested, had many followers, and is generally considered a good thing.
The same can be said for the Forgotten Realms. The whole thing can't be summed up as Elminster's world. Just because Ed speaks of his world through Elminster, that doesn't mean that he is the only character there. Personally I like the Forgotten Realms because it has so much going on, so many places to visit, and it continues to evolve. Some of the things they made for Forgotten Realms were really quite good while admittedly, some of it wasn't. Fine.
The Scarred lands is a darn good setting too. It's a darker setting for sure, but what I really like about it is that it takes the familliar into new and different directions.
Personally the only things I didn't like about Planescape (and I know I'm going to get lynched for saying this) was the art and the odd dialiect.
Personally, I applaud the way WotC has handled all their campaign worlds in 3rd edition. Greyhawk is setting neutral, so it isn't like it received 0 support like it did through most of 2nd edition. Forgotten Realms has had only a handfull of products as opposed to every other book being released as Forgotten Realms.
I guess the bottom line is that if X setting gets people to play and enjoy the game, how is that a bad thing?