People would just like to make things more complicated than what it really is.Normally, you would see the 'play', 'pause', and 'fast forward' buttons in a media player keyboard. But what happens when they are all put in a mouse? This would naturally get space that the traditional right and left buttons holds, so they were transfered to the front. How would you like that?
Link: The Gadgets Weblog: World's Ugliest Mouse?