Really, WotC may as well have just said "Y'know, we're not even going to pretend to have a default setting this time around." How is this a setting? It sounds like they're just saying that the world is full of dungeons and monsters and crap, but there are some standalone kingdoms and villages that don't affect each other and the PC's can come across if an adventure calls for it. That's not a setting, it's just a blank slate for the DM to slap adventures onto without any real concern for a "big picture". Not that there's anything wrong with that - there are plenty of ways to game other than mine, and none of them are any better than the others. (Well, of course MY preferred style is best...) There's no need for a developed setting to be included in the core set - just don't pretend that there is one when there really isn't.
Of course, it's still early and all we have is a blurb to go on, so my indignation may turn out to be unfounded...