The Motor Vehicle Safety Compliance Act of 1988 ended ALL importation of grey market cars with no real evidence of any difference of safety between USDM Vehicles and non-conforming vehicles such as JDM vehicles and GDM Vehicles.
The safety of vehicles from the grey market are nearly, if not the same as a USDM vehicle. There are no differences big enough to cause a grey market car to be vastly less safe as a USDM car.
The importation of a grey market car will not hurt the company that made them in anyway, because it is not a new car. 15 years is a much more reasonable limit, especially for us car enthusiasts that want cars that we can't currently have.
There is no reason why the law can't be relaxed to 15 years when there is little to no difference in the safety of non compliant cars.