That airplane was perfectly respectable by the standards of its day, but we now can do much better. One reason we don’t do better is that new planes have to compete with newly built planes that shouldn’t pass modern standards while new designs built to modern standards cost millions to get certified and are much more costly to insure until its proven they are safer. Most fail because they are not a “Cessna”. Also, building a new plane with a new engine is double the risk and trouble so new engines cannot succeed unless they can GREATLY outperform the known engines that the planes were designed for.
And, why is this the case? Well, it’s unfair, but the FAA gets most all the responsibility even though the lawyers really should share it along with the pilot community.