If it really is "much ado about nothing" then why change it? And vanity cards do change all the time, but they've never changed this drastically.
In the late 80s, the sky blue w/ white castle with "when you wish upon a star" playing was introduced. It announced to the world that this is the Walt Disney Pictures group and we are ready to play ball!
In the early 90s, they introduced a more serious "vanity card" as you call it for the live action movies (like Rocketeer, etc) that simply stated "Walt Disney Pictures" in a serious type-face over black.
The Vanity card changed once again with a CG opening, but it still said Walt Disney Pictures. It was to be used in front of all films under the Walt Disney Pictures banner, be it animation, pixar, or live action.
But now... it just opens as "Disney". Again, I ask why. If the division is still to be named Walt Disney Pictures, why change it?
That is something you still fail to answer. If you don't have the answer, that's fine.