The problems with the idea of a so-called idiot-proof aircraft (that can’t spin and/or stall, or don’t need rudder pedals), like the Ercoupe, Long-Eze, and many others, is that it is just a dream, no more no less.
The Cessna 337 was supposed to be the safest twin there ever was, but the accident records tell another tale (Swedish Coastguard had several, all lost, some just disappeared over the North Sea), John Denver lost his life when he managed to deep stall his beloved Long-Eze.
Here is an interesting article by Richard Harris about the safe plane:
https://close1d2.org/wp-content/uploads/2017/11/BewareTheSafeAirplane.pdf?3a1a6d