You have just as much glare on a matt screen, it's just defused. If you angle a glossy screen correctly, you'll have much less glare than a matt screen.
A properly-angled matte screen will have less glare than a properly-angled glossy screen. And a matte screen is less finicky about how it's positioned, which is an advantage when you are seated in a place that limits your options.
Plus the glossy bezel around the usable area of the screen acts like a mirror. The brightness of the active region overwhelms a lot of reflections, but that doesn't apply to the black bezel.
I work on a glossy iMac, and I've been tempted to get strips of matte black material with which I could cover the bezel, using magnets to hold them on.
