Why in heaven's name would you want somebody without a medical to be able to fly a six seater twin engined aircraft? I certainly wouldn't want to be aboard !
The medical requirements as they already stand now allow "private pilots" to fly those aircraft with a Class 3 medical certificate that only has to be renewed every 5 years. Lots can happen in five years. The aircraft we're talking (up to 6 seats, 2 engines) about are usually general aviation aircraft flown with a "private Pilot" license.
Under current medical requirements, persons flying LSAs (2 seats and under 12xx pounds, and a stall speed of 45 knots) are allowed to "self certify." That's to say, they only need a valid drivers' license and a general knowledge of the types of illness or conditions under which they should not fly. Data so far (the past 15 years or so) indicate that there have been no accidents among this group that were attributed to medical issues.
Considering that everything which disqualifies one from getting a Class 3 medical also precludes you from an ordinary drivers' license, it's not that illogical. The only real difference between the Class 3 requirements and the drivers' license requirements is all the documentation required to be submitted to the Aeromedical Examiner to get a special issuance.