This layout will be typical of a FPS game style game play with the RPG controls incorporated.
The reasons behide choosing such a layout is because the WASD style layout is used through PC gaming and making radical changes will confuse gamer already used to this style. And also it works plain and simiple, it feel more natural then using the arrow key(for example) to move.
The Xbox360 controller layout is also a FPS style layout, I choose to very a layout similar to whats in COD:MW for a couple of reasons. The first is that again this style layout works very well, the buttons you use most are the most accessible. Also the COD Franchise is one of the best selling game out there, millions of people play it on xbox360. Therefore millions of people are already used to this layout, making it easy for people to pick up the controller and start playing straight away. There are also the Buttons used for the power/skills, that blend easily into the FPS sytle controls.