Z, you talk about coming out with an innovative concept that is so crazy that it works. Would you say that the Deltawing is a good example of this? I mean, it was made with complete disregard to any rules set, and had enough luck (read: money) to convince the ACO that it should be allowed at LeMans.
If you don't have rules on a class you do, eventually, find someone with enough "resources and skills" to find what works the best, then they dominate and keep getting faster until they start going too fast for the squishy bit behind the wheel. This is what happened to Can-am and Group B if I remember correctly. This is what would likely happen to every race series that is out there if they're allowed a truly "open" rule set.