Why does the Xbox controller have non-symmetrical analog sticks?

The image below shows the controllers of the three eighth-generation consoles (Xbox One, PS4, Wii U).

As you can see, both the PS4 and Wii U controllers have symmetrical analog sticks, which seems like a very natural design choice. The Xbox controller, however, has non-symmetrical analog sticks.

What is the reasoning behind non-symmetrical analog sticks and are they intended to offer increased usability over their symmetrical counterparts?