Just read through this entire thread, found it quite interesting. And I'm wondering if I can offer an additional opinion from another perspective.
I come from a Kyosho Mini-Z racing background, and as some may know, Touring class racing for Mini-Z's is forced to run nothing but 100% realistic bodies. But despite this restriction (yes, the roof heights can be tall, and the bodies relatively narrow!) the racing is very competitive, even at the local level. The typical Mini-Z 2WD/AWD Touring main (even A main) is quite diverse, usually including at least one of each of the following bodies:
- Honda NSX Super GT
- Ferrari 360GTC or 430GTC
- Lexus SC430 Super GT
- Nissan 350Z 2007 Super GT
- Nissan GT-R Super GT
Considering most of the mains have 8 cars in them, that means we pretty much have only 1 or 2 repeats of a single body per main. The main thing to note is that Mini-Z bodies are allowed to be modified quite heavily, which results in the hardcore "racers" cutting out unnecessary parts, ditching molded wings for Lexan spoilers (rare, but allowed), and sometimes even cutting out the wheel wells to use a different wheelbase chassis underneath the body. We're allowed a lot of room to tinker with bodies, to make any body handle as well as it possibly can. I've only ever seen one case of domination, that's when the 2007 350Z was released and Reflex Racing found out that it worked well at a 2mm-longer-than-stock wheelbase. But that domination has gone with the release of newer bodies and the change of rules to allow any body to be modified as heavily as they are now. Now the playing field is quite even no matter which body you run.
Meanwhile, the "hobbyists" in favor of realism have nothing to complain about because Kyosho makes beautiful pre-painted Autoscale replicas, with nearly perfect detail everywhere, right down to the rims that come with the body. Of course you can buy an unpainted one and paint it as realistically as you'd like (there are plenty of Mini-Z enthusiasts who do just that). And while it is harder to win when going for strict realism, it's certainly possible, and one of the current World Champs can do just that with a barely modified Autoscale SC430.
Would it be hard to make more realistic bodies for World GT, and then change the rules to allow more realistic bodies to be made race-worthy, while keeping scale looks for those who want them? It really doesn't take a lot of effort, just some time with a dremel can turn a mediocre body into a wonderful one. I actually bought one of those 2007 350Z's for myself; in stock form it's sluggish and its rear diffuser drags on the track, but once the diffuser was cut out and the wheelbase extended, it pulled comparable lap times to the Pan-bodied cars. Having a wedge body helps, but certainly not as much once you modify a GT body enough -- and hey, my 350Z still looks like the real Super GT 350Z, just missing front canards and a rear diffuser.
Just some food for thought.