It seems the 145 is used very successfully around the globe for winching so who would you suggest caused the problem?
Well, I thought I was fairly clear on that. If you think the Mil Spec is wrong then it's the MOD's fault. If you think the aircraft should have been chosen with the Mil Spec in mind then it's the contractor's. I took it from your post that you think the Mil Spec is wrong and you blame the MOD. I took issue with you lumping in the RAF to those responsible; the RAF has no more influence over Mil Specs than the RN or Army.
If no-one is calling for the Mil Spec to be changed (does the wider RW community think it's rubbish?) then all anyone in the RAF could have done is waived a requirement for the contractor to implement a published safety standard. Why should any accountable individual take that risk simply to accommodate the aircraft selected by a contractor which would have been fully aware of the requirement and the specification? And, would another MFTS bidder have had grounds for legal review if a requirement of the bid had been waived after selection of the winner? (Almost certainly yes if they'd proposed a larger, more expensive aircraft with Mil Spec compliance in mind).