Agree wholeheartedly with JimL's comments here. Apart from the tragic and excessive loss of life, there are too many unnecessary accidents occurring that make dramatic headlines and unfairly erode public confidence in helicopters and the industry. The fact is that as machines they are extremely safe; their reputation though is heavily compromised by too many pilot-induced accidents. No, we don't know the cause yet I know, but "helicopter explodes in fireball" in Northumberland is yet another headline that does nothing to inspire confidence for potential passengers, even if unlikely to be weather related.
It is self-evident that too many mainly inexperienced pilots cannot be trusted to make their own safe judgements on weather. Of course it will be no easier to police than the current say 1500 ft over built up area rule, but at least it will serve as heavy guidance. As ST says, outside reported vis it will be harder to judge, but with the prevalence of GPS it's not difficult to learn and a good exercise anyway.