Asymmetry. It's not an accident that movement is on the left and aiming is on the right, both on controllers and PC. On PC, though, you can move the mouse to the left side of the keyboard and rebind your movement keys if you want to.

I've never heard a left-handed complaining about the traditional gamepad layout.

And yet, many popular console FPSes have optional "southpaw" layouts that switch the left and right sticks.

now they will.

Kid Icarus on 3ds was completely unplayable as a lefty.

any have stats of the left handed population in the world?

11% overall.

http://en.wikipedia.org/wiki/Handedness

Quote: "Globally, roughly 12% of men and 10% of women are left-handed."