Better yet, why not? A good screen protector (the boxwave ones are great) doesn't impede the readability of the screen, and protects your more expensive screen in case anything bad happens. Perhaps you accidentally tap your screen with your pen. Or you take out the stylus and a piece of pocket lint or grit is on the tip. Put the tip to the screen, and you'll hear the most horrenous screech, and have a bump.
Given murphy's law, your scratch will be right in the middle, and you'll see it. I'd rather replace a $13 piece of plastic than a $400 screen. Or take my chances with a refurbished screen if you send it in for warranty (which may have scratches, rough spots, dead pixels, imperfections, etc).