I don't get all the whining over AA either, why can't you just force AA in your video drivers?
Because a) Why should I have to do that?, and b) Because it doesn't work.
Personally I don't see the need to use AA at high res like 1680x1050.
Well, that's because you obviously don't care about visual quality. Personally I do. And I also have a 22" widescreen monitor that runs at 1680x1050 and anti-aliasing is still VERY important.
I think it runs fine on my system, especially considering it's over 3 years old except the video card (GTX 260).
I like the way you say you "think" it runs "fine", which is basically just another way of saying it doesn't run very well. I have a C2D @3.4GHz, 6GB RAM and an overclocked 4870 and I find performance poor. Games like GTAIV are why console ports have such a bad reputation.
I'm too busy playing the game to be looking for jaggies on the edges of polygons.
Let's expand on that argument, shall we? What about shadows? Too busy playing. Weather? Too busy playing. Damage modelling? Too busy playing. Rockstar clearly did care about graphics - otherwise they would have simply reused the GTA3 engine - so it seems silly that they ignored anti-aliasing, an industry standard. The trouble is it's a double whammy - it looks poor and runs like crap.
"The price of freedom is eternal vigilance."