Ah! But they are both based on the Mac OSX one originally! And personally it is one thing I really hate on the Mac OS. Especially the newer versions where the icons seem to be getting bigger and bigger with each new release.
In reality it was Apple's way of copying the Windows task bar without making it look too much the same. You have quick launch icons just like the Quick Launch bar in Windows, and open applications appear as icons, just like the taskbar shows open windows in windows. For me it is just too big and ugly on the screen. But as with anything, that is personal preference and as many people like it as hate it. And Mac users hate the Windows way of doing this just as much, although with only 3% of the market being Mac owners you have to wonder who is right.