On Mac OS X you can hide the entire toolbar by hitting the button on the right. Where do you think the 'quick access' toolbar should be, if not in such an obvious and easy to access place? It makes sense, to me, for them to be in that location and for the icons to be that size because of the purpose. They are there for one reason only - to provide quick access to a user's most used functions users may place any button they wish there, but that is the purpose of that toolbar. Those buttons are only there if the user wishes and can easily be removed.
