"The great majority (43 out of 60, with 98 fatalities) took place in unfavourable weather, underlining the problems with lack of training, over-confidence, poor decision-making and pre-flight preparation.
All areas which are dealt-with by the IMC rating.
I suspect that this is the cause of the majority of accidents in most countries. I think we need to be careful in the way we draw conclusions. The report is interesting and highlights that more regulation does not equate to better safety. It points to the better fatality record of the less regulated ULM sector and also concludes that flights from within the strong club environment generally result in fewer accidents. The report is an argument for devolving downwards the responsibility for flight safety to 'local' organisations. It comments on the unsuitability of a regulatory system aimed at the professional pilot for regulating leisure flying.
The report is not unfortunately an endorsement of the IMCR ! It points out the relative similarity of accident rates in the US and UK. Whether that can be turned into an argument for an IMCR I doubt. It may be an argument for a more easily obtainable IR, but the report does not say so. It seems more to support the concept of a sports aviation licence (lightly regulated but with a safety and skills ethos being strongly promoted at local level), which may or may not be ICAO compliant and I would guess would be restricted to day VFR, but I bow to others with far more knowledge on this aspect than I have.