I understand what you're saying about windows on top of one another at least implying 3D space, and as I've said the new heavier active window drop shadow seems to take that a little deeper. But:
We've had the "implied" 3D of windows on top of one another for a long time now, and it's never been anything but "the least we can get away with and still indicate 'on top". Certainly it's never called for other desktop 3D cues to help us out with the concept.
Deepening the shadow of the active window changes that a little, but if all Apple is doing is declaring the desktop 2" deep instead of 1/16" deep and then continuing to deploy elements in exactly the same manner, than that's completely pointless.
As I keep saying, if they plan to do something with that, something that is actually useful, then I'm eager to see the plan.
But just "Oh, hey, you know those windows you've been layering one over another for the last 20 odd years? They actually go back into space a little more! K, bai" doesn't do anything for me at all.
What apple is doing by making the desktop space 3D is rectifying a current inconsistency, further action by apple isn't really what is required. (Please correct me if I've completely misunderstood)
What I'm talking about is the, if you like, philosophy of the current UI (sounds very grand doesn't it ) The desktop should be 3D, it makes sense considering the current 3D nature of windows being on top of one another. Even with tabs in a tabbed browser. The tab protrudes out in front. All of the buttons protrude out, or try to give that illusion, and all the shading and effects point to the desktop being a 3D space. Why then is it illogical and inconsistent to have a 3D dock, to fit in with that.