Driving line is not evil, don't be afraid.
It's just another clue, among other things like physical objects on the tracks, blinking gear reminder on the HUD, tire sounds, FFB... etc.
It's obvious enough that the driving line is not always the best line, and the braking points are often way off. Any mildly experienced driver can tell that. So you can by all means avoid being confined by it. Take it as one of the clues, as some kind of reminder, and use them with your own judge. In this way, you take the advantage, you are in charge, you are served but not controlled by it.
Of course you won't actually need it once the track is familiar enough, there're full of other visual clues anyway. But it's still useful when the visual condition is bad. For frame rate issue, I run 720p. And the TV is not big enough, and I'm a little bit too far from it. For smoothing the motion or other optimization priorities, game updates make the graphic coarser and coarser. So I do miss a few things in some occasions, like Ascari in the dark afternoon, or rainy Brands Hatch, not to mention Le Man and Nurburing at night....
Purists might argue it's best to turn everything off. But I feel this video game, wonderful as it is, is still unavoidably very lacking in providing a whole sensational experiences of driving a real car. So, I'd like to have as much information as possible. I'd like to have the right to decide how, which and when I use them or ignore them. And that's not event to event, but second to second, or by even shorter periods, like I glance the mirrors from time to time in real driving. (Oh, the presented line in GT6 is not as intrusive as previous GTs, which is good thing.)
If I'm driving a real car on a real track, of course I don't need and don't like any additional lines on the tarmac to guide me. I don't even have much time to glance those dials etc. But, oh well, you know, I'm sitting on my couch, holding a plastic wheel, and facing a not-very-big TV, in which I can't pretend I'm doing the real stuff. Sad but true.
