Well...
Rear engine/front wheel drive is not good for balance. With the engine weight in the rear, the car's tendency to shift weight back would be compounded, then take the front wheel drive that would have even less grip thanks to the weight being back by the engine/rear wheels, and you would just get a car with a funny drivetrain and no grip.
As for front/front racers... Im sure there are tons of alfa romeo, acura and mazda gt drivers that would be sad to hear of the popularity of their racecars is almost totally unknown.