I think that it is not the worst idea ever.
But that way we have a problem of hotlaps... maybe we'd need to separate rankings, hotlaps with stock cars and tuned ones...
But, to be exact, creating setup is a way of tuning. One would say, the truest way of all.
But, to the point: there's a game called Nitto 1320 legends. It has the best tuning system of all times, in way of buying/installing new parts etc.
I'd be veeeeery happy, if something similar existed in LFS, as well as real cars and tracks (call me deviant, but especially I'd like to see mountain passes).
But it's kinda dreaming, since:
a) it of course won't happen
b) I'd doubt if S3 even will be released, but still I hope so.
Edit:
4 times "but" in a row... weeeird.