More on the iTunes rounded windows

These are some pics I found on internet, comparing the window's corners from the previous incarnations of iTunes, with the newer releases.
Like I said before, I really don't understand the idea behind this, and I certainly hope that the next release of Os X does not look like this globally.








What really puzzles me regarding this whole "chopped windows thing " is why would Apple do it, and then again, why only on the iTunes window?
Would this be a preview of how the windows will look on Leopard?