Because some people (including me) cannot stand using screens that reflect everything like mirrors, are prone to glare, very easily get smudges, over saturate everything on the screen, you get eye strain after extended use, and are harder to clean. I think that summed everything up. I especially can't stand using a screen that is basically a mirror, I can't concentrate when I see everything that is behind me on the screens. Glossy screens are great for people who can live with all of it's flaws, but some people just can't use them.