If you don't like this idea then you, along with most of the people responding, must be a recent fan. I think the main reason this isn't done is because only the France family could afford to supply the cars and Humpy Wheeler supply the "showmanship" for it.
I was involved in just such a race that was held at Charlotte Motor Speedway in the the early ninties. They supplied Cup cars for several retired drivers, some in their sixties and seventies, to race on a specially constructed oval in front of the main grandstands that replicated the old Bowman-Gray Stadium track.
Two things stood out plainly after the race was over. One being, Once a racer always a racer, proven by the "heart" shown and the , shall we say, creative lines taken through the corners by real racers. And the second thing being that all the high tech shop personel like shock technitions, weather men, and fuel chemists would have to find other work or learn to run an English Wheel because a good body man would be an essential part of every team. And not to "tweak and finese" the pampered and highly massaged bodywork of today but to put the fenders and doors back on after the real racers got done with'em.
I was there and got some killer footage and while it rained off and on, there were few that left because they knew they were gonna see something very special that day. It really was special for me because I had seen many drivers that I had lettered cars for win on our local track but this was the only time someone I had lettered a car for won at CMS. Had to pull for Elmo since Jr. had gotten too far behind for even him to catch up. You know that his chances for a break went out the window when he bumped France in the pace car. LOL