From what I've seen and heard, the modern glare screens Apple uses on the Retina models has less glare than the predecessors.
However, I see Retina-quality screens from a few other manufacturers, and those are offered in non-glare variants.
A friend of mine has a 2011 or so MacBook Pro with a brushed/matte screen and it undeniably has less glare than the Retina screens. In fact it almost has no glare at all. No idea why Apple discontinued that.
Æsthetic preference?
I believe color reproduction is better on the glossy screens.