Below is an excerpt from the article: "If you're a new user to Windows 8, one of the first things you might ask
 is, "where's the Start menu".  Microsoft had to do away with the Start 
menu and create the Start screen because the world is become more 
reliant on mobile devices such as smartphones, tablets, and touchscreen 
laptops. ...
The traditional Windows metaphor such as the Start Menu (and several others: such as windowed applications, drop-down menus, etc.) don't lend themselves well to the newer mobile device technologies like high resolution touchscreens that don't support a standard keyboard and mouse. " (read the rest of the article)
 

