I know what you mean. I sort of liked the Nordic take on the origin story (Primordials versus Gods ~ Giants versus Gods). That said, I also really relate to the kind of changes Mike is making to the setting. Not the specific changes. I mean, I like that take too-- mortals that became gods through a struggle with cosmic beings and that, as a result, are more involved in mortal affairs than your usual pantheon. That's cool. But more what I mean is that it's exactly the kind of thing I do to an existing setting when I'm doing my own campaign. I'll come up with a great story idea and then morph the backstory of the setting to enhance my campaign story. For example, in one long running campaign, I ended up almost completely re-writing the history and cosmology of the Forgotten Realms as we went along.
So, as an example of a DM doing his thing, I see where Mike is going. He probably had some nifty idea for his campaign story and ran with it. It means that his game will probably be more fun to watch because as a DM he's really invested in the game.