I think you find the nostalga of the Piper Cub is its appeal. Post World War II, saw the Cub mass produced and for many, the Cub was the plane they learned to fly and earn a pilots licence. As a Pilot myself, many of the Older gentlemen tell stories of how they learned to fly in a Cub. My father learned in a Super Cruiser, which is a bigger Cub with a little bigger engine. Cub's lend themselves to Scale very easily and still retain an ease of flying, were as a P-51, flies like a P-51, it's not forgiving with a high wing loading.