This is lame. Planes exist. Planes crash. It sucks but we pull ourselves together and move on. Now, it's been awhile, but I thought I remembered being able to fly a sea-plane in Vice City. Are they taking out helicopters too? The number of cities certainly shouldn't have any impact on whether or not you can fly. (I spent most of my time flying in San Andreas, mowing people down in Vegas telling them they were all living in sin :D I never really bothered ever flying long distances.) So as far as city size is concerned as an excuse I think it's lame.

 And certainly, 9/11 was a terribly tradegy but what about the train bombings in Madrid? Or the Underground attacks in London? A central theme of the game is unrestrained, chaotic violence - certainly not the point but an essential option. If they had included the twin towers that would have been an atrocious slap in the face. But removing a daily element of life because some schmuck decided to use it as a weapon is dumb.