I wanted to talk a little bit about settings and, also, explain why I think the Realms were blasted into orbit.
Let's get the Realms issue out of the way. Why were so many changes done to the Realms? Why did they force the 4E default assumption onto that setting? Because they have made the Realms their flagship setting. As such, the flagship setting NEEDS to handle all of the 4E default assumptions as closely as possible. Combine this with a bit of bloat from previous supplements.
I do not think that this is going to be, or needs to be, the case with any other setting. Settings, by their nature, have their own unique requirements, such as deities, races, classes, even feats. There is no requirement for a setting to use, let's say, the list of Gods from the 4E RAW. They won't even have to use the 4E cosmology. Maybe, for the sake of being easy, the Shadowfell and the Feywild could be used, but they don't need to be. Appropriate fluff can be written for each setting to explain any special abilities that a Class may have, such as Fey Step.
Will it be more work in 4E? Maybe, but I don't really think so. I think that any good setting is going to deviate a bit anyway and establish its tone and mood. It's just a small step to go from there to adding in some details about that setting's unique cosmology.
What about the Races? The Dragonborn and the Tieflings, for instance? They are in the PHB, but that does NOT mean that they have to be common races in any setting, if present at all. It would be wise to have them there in some small way, so that players could play what they find in the PHB, but that doesn't mean that they have to be common, even if the PHB races in the past were. What about the other races? What about gnomes, and such? Well, they're in the 4E MM as playable Races, over 11 of them I think, so that shouldn't be a problem to include them in the Setting.
What about a setting's tone? This could be achieved by a few specific rules. Maybe characters don't have as many Healing Surges available in a day, or maybe the Races will have access to different, new Racial feats and abilities that more closely fit the setting (lots of potential there, actually). New Feats? Definitely should have those. Optional rules, yep. Hell, even new Classes or new abilities or Power sources could be included, depending on the GSL and what it permits.
The only reason I bring this up is that I've heard some people say that certain settings would not be possible using the default 4E ruleset, that they would be as damaged in the process of making them conform as the Realms were. I don't think this is really the case. The Realms were forced into a little box because they are the flagship. I think that any other setting should, and WOULD, be allowed to remain unique to itself. And I don't think the rules will hinder this.
Sorry for the rambling nature of the post. I'm writing it in bits and pieces this morning as I can. :-)