thaimin, I see where you're coming from, or I at least think I do. This animation screen goes well beyond the displayed scene (which happens to be animation), and provides somewhat of a distraction, as you're pointing out, the "psychology of waiting" deal.
Most everyone wants everything to be fast these days. While this is not always possible (lightning fast boot times in this instance), the animation reduces the anxiety during this time, as opposed to the familiar Windows symbol appearing, which in fact, doesn't happen instantly. There's a noticeable wait time for it to occur. So the animation (of the users choosing) helps to "lessen" this time, or at least the user feels this way, which is the main point here.
It's similar, although the time frame is greatly different, to the event that I had last week. I took my car to have the timing & drive belts changed. It's about a two and a half hour job. Normally, this time would have dragged out, between reading magazines and looking at that CNN News channel going.
Instead, I carried my notebook computer with me, I was doing some work (setting up a virtual machine), and that time flew by. I got there at 12:45 and left a little after 3PM. The distraction of working with the notebook not only made the time go faster, but I was more comfortable as well. No backache, no yawning, and I felt good. And not once, did I become concerned with the waiting for my car.
A much different setting (than the animation screen), but the end result was the same. Some calls it "killing time", and it works.
Thanks for coming back with the more clearer view of things.
Cat