An excellent analysis, by Patrick Smith in his latest "Ask the Pilot" column in Salon, is the most realistic description of the air-travel mess I've seen in the general press (if that term applies to Salon).
You should read the whole thing, but mainly: the culprit is not unusually stormy weather, aggravated (or not) by climate change. It's not antiquated air traffic control, though antiquated it certainly is. It's not a plague of little private planes.
Instead it's the collision of two big and contradictory facts: one is that the U.S. is short of runways in big-city airports, and isn't building any more. (Do you want another airport by your house? I do, but that's me.)
The other is that the airlines' scheduling practices aggravate the runway shortage. The airlines sensibly view "convenient" scheduling as the key to their survival -- and convenience means a lot of flights trying to take off or land all at the same time. Their shift to regional jets is efficient in many ways -- but it means that more take-offs and landings are required to get the same number of passengers to where they're going.
Here is the big conceptual difference between people who have flown airplanes even in the crowded East Coast corridor (or LA / SF or near O'Hare) and those who have not: Pilots have seen first-hand that the only scarce resource in the air-traffic system is takeoff/landing slots at 15 or 20 big airports, and positions in the queue for those slots. Otherwise, the skies are virtually empty and most of the country's 4000-odd airports are underused. Of course that one scarce resource is the same one airline passengers confront day-in and day-out.
Read Smith's article; also, this analysis by pilot, flight instructor, and longtime developer of Microsoft's Flight Simulator, Bruce Williams.
Now, why is my flight so late -- on China Eastern, or Shanghai Air, or Shenzhen Airlines? That has more to do with the People's Liberation Army's ongoing control of the Chinese airspace. For another day.