Again great points, however I counter with this. You bring up the castle parks, isn't that really just a collection of themed areas with no real overarching theme? Now some, and I'll venture to guess you will be in this group, will say that its Walt that is the overarching theme. However I say that is not so, it was Walt who brought different themes into one location yes, but he didn't really tie them all together to be one larger cohesive theme. Its different areas of the park that guests can move around that have no theme that ties one to another. Or to say it a different way, the only overarching theme is imagination. Which can be said about any Disney park no matter the theme. Its the imagination that allows us the guest to disconnect from reality and believe we are on an adventure in the jungle, or flying in a pirate ship around London and into Neverland, or now walking into a land filled with your favorite characters from Pixar or soon to be Marvel. But there is no overarching theme that says what I just experienced while riding Jungle Cruise is somehow tied to me riding a flying pirate ship over the streets of London other than imagination.
All Disney parks are really is just an extension of our childhood imagination. There is no overarching theme needed more than just that. Now that is not to say that you can't have parks with different focuses. For example animals or technology with Animal Kingdom and Epcot respectively. However the idea that a park based on California located in California was a good focus for a park was flawed to begin with. And the fact that Disney changed directions is pretty clear they have decided it was a focus of the park that couldn't be maintained. So the focus of DCA will now be similar to Hollywood Studios, with the focus on the imagination of bringing characters and their worlds to life.
I will agree that its the execution of the themed experiences that set Disney apart from the competition. But it is ultimately the public that will determine if the execution is a success or not.