The Dock adds a whole new behavior: Object annihilation. Drag an object off the dock and it disappears in a virtual puff of smoke.  This is the single scariest idea introduced to the Macintosh since the original bomb icon.  How would you feel if you spent eight hours working on your first Macintosh document, only to have it disappear entirely when you try to move it from the dock to the desktop?  Pretty disorienting, no?  This is a completely unnecessary concept for the user to have to learn, particularly in such a painful way. Makes for a "hot demo" though, doesn't it?