Not if you're only working on one document at a time. Being distracted by some other stuff on the side is not always a benefit and many editors are surprisingly hard to set up to center documents on the screen while blending out anything on the sides.
Being distracted is never a benefit, but being able to see two or three files together and compare them is. At any rate, it's just extra space that you can leave blank if you wish. I see no upsides of 4:3.
