Motion blur adds a touch of realism to images as it mimics how a camera sensor captures motion according to its shutter speed.

Yeah but this is only realistic and appropriate in specific situations, for example motion blur would be appropriate in a racing game.

In something like a first person shooter, blurring the whole screen as you turn/pivot looks ridiculously bad and is incredibly immersion breaking. Your eyes don't do that at all, your brain just cuts out your perception as you move the focus of your attention.