Just want to speak up for the casual, non-veteran, non FPS-playing player who has deliberately chosen Free Aim for two reasons:
1) My first few trips into GTA:O Auto Aim were painful, stupid, grief-fests filled with manic idiots attacking and killing low-level players fresh out of the tutorial. Instant, perfect auto-aim at 200 yards meant that looking for cover or hopping into a car to speed away were pointless. I didn't like free roam at all because every 11 year old had aim as sure as an AI Cop with a serious antisocial attitude. Screw that.
2) I decided that I'd enjoy actually developing my own skills by committing to Free Aim, taking my chances, and learning how to truly compete or fail.
Guess what? I was absolute sh*t at first on Free Aim and got my ass handed to me by players, AI, and even the friend I talked into joining Free Aim with me. But I've improved and am getting better all the time. The game is much more exciting and rewarding when you have to be careful to plan your shots, look for good cover, and study the AI's behavior closely.
And now, if someone headshots me while I'm flying down the highway at 110 mph, they DESERVE a feeling of accomplishment, and I do feel respect for them. That takes real skill. Skill I would be a little proud to develop.
That said, I don't blame anyone for choosing Auto Aim. I mean, it is the default GTA option and has been since at least the days of GTA3. I see no argument to be had here. I simply prefer my choice of Free Aim for the reasons given above. Choose the game you want to play, and enjoy it.