The quest to come up with the perfect personal airplane, which would sell in droves, was probably the dominant force in the evolution of general aviation ever since the post-World War II boom and bust. It looked easy: it only needed to perfectly combine ease and cost of operation, ability to carry the right number of passengers and operate from most all airports in the country. Piece of cake.
Aeronca, Luscombe, ERCO, Piper and Cessna, among others, all eventually came to the conclusion that the future for mass-marketing airplanes was wrapped up in something that had four seats and on the order of 150 HP. ERCO (the Ercoupe folks) never went past a prototype. Aeronca and Luscombe gave up after limited success, while Cessna and Piper went on to fight it out for decades, and Beech and Grumman-American tried to make inroads.