I've driven Road Atlanta IRL and on a couple of games. IMO, those iterations aren't done very well. The version of Road Atlanta for rFactor isn't very good. The turn 3 and 4 and the esses feel all wrong. Forza2 did a little better, but there are a couple of key areas there that feel really bad.
The problem, imo, with real tracks in video games or race sims is that the driver is essentially driving someone's interpretation of that track. I doubt that any of the available race sims/video games get RL tracks right as a result. I haven't driven iRacing, and likely won't for some time, so I can't speak to the realism of those tracks.
I can still very much see the situation where someone using a mouse would need the car to react within the limitations of the input device. This, of course, would necessitate setup options.
Here's something else to ponder, what effect to control systems have on an individual's setup?
I'm making the leap in logic that nearly all the responders to this thread are playing on a wheel. There are people that are WR holders that drive with a mouse. The overwhelming point is that different control schema necessitate the ability to change the way the car drives.
As an example, my experience playing LFS changed pretty drastically about a month and half ago when I bought a new wheel. I started playing LFS on a wheel that was orphaned at my apartment; it was an old Logitech Driving Force without the power adapter for the FFB. I bought a Logitech DFP the day after Christmas and pretty much had to relearn how to drive.
I think the option to tweak setups needs to stay in the game. I think the experience of playing LFS would impacted pretty greatly if setups were limited or servers forced a spec set.
I've tried the tiered system and think it's a pretty good system to help teach clean racing and better car control. Props to S3 Racing for coming up with something unique, using an under used car to help make racing in LFS better.