I think Ikarus is onto something, but it seems there's a point here no has touched upon: this rude behavior is symptomatic of a general debasing of our culture, from the mosh pit devotees to the concertgoers. You could debate for hours they whys and wherefores, but the pattern seems obvious to me. I share some of Ikarus' frustrations - the coughing, late arrivals, chatterers, the cell phone addicts, and uninspired readings of great music. Doubly annoying since we have a superb orchestra in our city, but it at times ain't easy to hear it for the noise in one form or another. Civility is indeed a dying art.
Re the point on the mechanical nature of the performances - it can't be easy for the musicians to be on fire for every performance. That is not to excuse a run through of a Beethoven, Schubert, Mozart, what have you. But we all have our flat days. One poster here mentioned a conductor who chose Baltimore, citing its collective desire to improve. That strikes me as an extremely astute observation by this gentleman. Complacency, whether manifest in the Cleveland, New York, or the Frog Creek Lower Symphonic Orchestra and volunteer fire department, is not conducive to inspired musical production. I guess the trick is to pick your concerts on the days when the musicians are "up" :>). (Don't know how you'd do that, of course.)
That's why I go to few concerts these days; it's also why I've made a substantial investment in home theater. Can't take the Philistines in the concert halls or the theaters.
Diatribe is over.