Simple, it's a place where you can build your own kingdom. It happened a few times in my campaigns. Yes we did a lot of reset. But the fun is being able to do it and how it will turn out.Personally, I have no need of such a product, and neither do most existing fans of the setting. They'll only get so much out of it. You seem to want to capture a new generation of fans for the setting. This is not in any way a bad idea.....but I think that the question then becomes: "how do you make Greyhawk seem as awesome to people today as it did to the early gamers?"
And that's kind of tough.