Yes, but the IMC rating has been with us for a very long time and a great many hours have been flown by IMC rated pilots.
Are you suggesting that if there has only been one IMC related accident in that time the evidence can be ignored as not statistically sound? It seems to me there is no evidence the rating is unsafe because essentially there have been no accidents. The accident rate of course many increase from zero but applying your logic it would need to increase by a great deal over a long period of time before the rating could be judged unsafe.
How many hours and decades would you want?
Moreover how much more or less statistically sound are the proposed changes? There seems to be no evidence what so ever to support the changes.
It feels to me someone just thought it was a good idea which is in fact exactly what you are suggesting.