Oh wow. The Ercoupe. Sadly, the original design was found to be an unsafe plane due to very poor spin recovery, but mostly due to being under-powered for its airframe. It actually ended up having a higher-than-mean accident rate for the time which defeated its raison d'etre. There are still more than a few (~200) actively FAA registered today though I'm certain with engine power and control surface upgrades.
It turns out that pilots DO need uncoupled yaw, pitch, and roll controls in order to maintain authority and/or recover from certain behind-power-curve conditions, but they didn't know all the edge case stuff back then.
Many of these early designs, including other notables such as the Dyke Delta, sacrificed general airworthiness for a single notable flight envelope performance characteristic. In the case of the Dyke Delta, very efficient high-speed cruise, but it's far too sensitive to CG, has little practical cargo capacity, poor stall approach/recovery (think snap-stalls), very poor visibility, and longer take-off/landing runway requirements.
I have zero doubt that modern fly-by-wire controls can enable a very car-like piloting experience, but I also have zero doubt that there's no way such an experience can be brought to the GA market that's remotely price-competitive with current non-fly-by-wire offerings.
Additionally, the regulatory environment (at least in the U.S.) still mandates pilot proficiency without any dependency on these flight aides. To use a (very) rough analogy, though we have auto-driving features on modern automobiles, they can't be enabled when obtaining a driver's license. Like with many other human activities, you need to train and certify for the statistical tails though you operate in the fat part of the curve.
The automobile market is also absolutely HUGE with (exponentially) lower upfront regulatory compliance costs that can potentially offer an return on investment to absorb the R&D of fielding a few "radical" early "luxury" models to enable the mass-manufacturing of a "base model" and achieve economies of scale.
The general aviation market is TINY and its large upfront regulatory compliance costs only effectively allow for a new manufacturer to field ONE model for many, many years so that ONE model must be designed VERY conservatively and, essentially, only iterated throughout its lifecycle--never fully redesigned.