Over the years, we have had a conflict between two groups of users: GUI-friendly and CLI-friendly. Mostly the CLI-friendly people think that the keyboard is faster than mouse while the GUI-friendly people think that the mouse is faster. A research by Apple shows that actually it is the mouse that is faster in most cases although people think the keyboard to be. However, it is not the metrics that matter; but the mentality that is developed.
A programmer typing in full flow is very unlikely to break his flow and hold the mouse. He probably would prefer the whole window to be controllable from the keyboard. That way the interface is letting the programmer do his job without being distracted towards using a mouse. Emacs is a classic example of this.
However, people who work primarily with the mouse like desktop users who are copying files or playing music can use the mouse with ease letting the other hand rest.
Apple and Microsoft provide a nice GUI interface and are doing good business because most of their users are GUI-friendly. However, linux allows choice. There are great GUI windows managers like Enlightenment and there are also tiling window managers like awesome.