While DRJAD is undoubtedly right that all sorts of improvement are possible there are some basic issues he has not brought out.
New aircraft and components are being produced that design out some of the problems, however much of the GA fleet is old. My own is worse than most, the prototype having flown in 1938 with this one constructed ten years later.
It is not uncommon to find oneself in a commercial airliner that is over 20 years old or in a Cessna or Piper from the 1970'es. Retro-fitting technology that was not readily available when the aircraft was designed is an expensive business.
When a design is certified a Type Certificate is issued to the manufacturer. Subsequent changes require a Supplemental Type Certificate (STC). While the costs of obtaining a Type Certificate are amortised over all production aircraft the cost of obtaining an STC are met only by those owners who choose to have that particular modification.
While new designs introduce improvements they also introduce new problems. It's an old adage that you get owt for nowt and higher performance seems to go hand in hand with more challenging handling.
Mike