well, gta4 came out like 8 or 9 years after 9-11. a lot of the game's humor came from making fun of post 9-11 new york. 3 did make some changed due to 9-11, from what i understand. i never heard that about the final mission; it's possible that the plan was to do something with a plane on it but i'm sure the version we all played was the original one to actually be released (you do shoot down a helicopter in the final mission; i think that's the case in all versions). but it's pretty much been confirmed that that's why they took out the darkel character, who was a homeless guy that had you make terrorist attacks, and supposedly they also changed the police car designs so it didn't look like you were attacking NYPD just after the whole 9-11 thing. but they did leave the plane in (although it was really hard to fly, which may have had something to do with 9-11). anyway, there were planes in at least the first 3 games to come out after 9-11 (i really don't remember if they were in vice city stories or liberty city stories) so i doubt that they suddenly took them out several years later because of that.
I never played IV. Should still do that. I mean, I did for like five minutes, when I was really stoned. I flew threw the windshield and died. More than once. Impressive upgrades, but I never got the game. I've played III, vice city, and SA extensively.... own SA. Great fun, played it just a few minutes ago. People talking about wanting planes need to realize that the physics where way off in SA, it's big but not THAT big, you can fly accross the game in like 45 seconds flat. Which is fun, but the whole game is very dated now. It also causes draw distance problems, where you can't have such a detailed scene going on, because when you fly back to bomb that cop car, or jack that car, or whatever, it's gone, which is really a pisser. To make a more consistant, modern game experience with realistic physics and using a reasonable amount of computing power, it makes a lot of sense to ditch the planes and focus on the ground, making you actually play GTA as opposed to spending your whole time dogfighting horribly weak AI pilots and totally slaughtering anyone in your way. It's fun, but just play SA if that's what you want. This is the same reason they can't remake the whole SA (or why I would not try, if I was them): the map is suited to a particular style of game, and they probably want to make more impressive realistic play, instead of being a VTOL-fighter-jet-flying (and bailing from to ram cops and surviving at what would be supersonic speeds) supersoldier like in SA. It's really a more fun game when you start over, in the ghetto, and remember having to try to bust successful drive-bys, instead of being a crazy one man army with nothing to do but blow everything up.
^unfortunately, even with the on-the-ground focus of 4, it's still fairly common to chase some asshole around a corner and find that they've vanished into thin air.
GTA is my favorite video game series by far. I will have to buy a 360 again when 5 comes out, Im sure it will be crack. Right now the only game I play is San Andreas on my computer with the SA-MP (multiplayer) mod , really never gets old
GTA games are always awesome. I likehow they took 4 more into the realistic physics and less arcade like, but I really miss doing awesome stunts on my motocycle in SA. Ill be buying it the day it's released. Hopefully the PC port won't be as horrible as 4 was.