The US magazine Flying looked at the MU-2 several times over the years and at the accidents. As you say it was a hot aeroplane - a properly trained pilot could handle it and it delivered superb performance but it could very easily get away from an irregular flyer who didn't keep their training up to scratch .
These days the Insurance companies would probably make sure it was only in the hands of the proficient - no coverage or astronomical (even MORE astronomical!) for those not training regularly