It doesnt need to make any sense ...its the CAA . Of course you should be able to do the training in singles . I have flown , and been flown , for many hours IMC in the UK in a single and personally didnt feel any cause for concern !! It was safe and sometimes legal .... A full up 109 or 355 will be coming down too in the event of an engine failure . Also dont forget that singles and twins only have one Xmission etc etc At the end of the day do i believe they will relax the ifr rules and get more people rated and therefore not clawing around low level ....No . They have never shown any common sense in the past and will not change .