Maybe not! That would require changeing the whole development of the beetle, and maybe the intermediate stages would not be beneficial. To give a terrible example, if you have a car and need a camper, you could rebuild the car into a camper but you would have to change everything and would not have a useable car for a long time. If instead you bought a trailer with a tent on it, you could build a perfect camping trailer over time step by step and have still use the car.