On Sunday President Obama wore khaki shorts to play golf, giving us a glimpse of the presidential gams. The Huffington Post has a poll asking whether shorts are appropriate on grown men. The majority opinion is "Yes--now shut up, all you self-appointed style arbiters, and let us wear our man-shorts and Tevas in peace."
My main complaint is one of aesthetics, not age-appropriateness--most shorts are just not elegant. The proportions are clumsy and ugly, especially when paired with flip-flops. They tend to look too casual in an urban environment--and really, are you going to be that much cooler in shorts than in light linen or cotton pants?
Having said that, I think shorts on guys are fine at the beach, in your backyard, or yes, playing sports. And our president would look suave in a burlap sack.