I don't buy pre-packaged campaign settings very often. When I do, I hardly ever play them out-of-the-box; I make a plethora of changes and melge it into my exisiting campaign as a faraway land, new dimension, or something.
You know, like everyone else does.
All of that to say, the more interesting and different and cool the campaign setting is, the better its chances of me picking it up. Who publishes a campaign setting (WotC, third-party, licensed product or not, etc.) does not matter as much as the amount of imagination and detail that goes into it. I think most people would agree.