FormulaFox No1kiwi
Nobody copied it because it wasn't legal anywhere else. Even where it WAS legal, it was racing under special approval that other groups were unlikely to get because it was the result of the program being run by the company that was the owner of the series when it first came about, and then became an important partner in the series it was then allowed in.Also, the concept WAS copied - and the company that copied it got SUED over doing so. (and the copy failed because they put a junk powerplant in it)
Put simply, nobody else was going to be ALLOWED to run it.
The concept, no matter how much you want to paint it as such, was neither flawed nor a failure. It achieved it's goals - it ran competitive speeds on half the weight, half the power, and(a little over) half the fuel.