Some sensible comments here from DB and Shy.
But Shy, what sort of actual weather minima might you suggest for VMC to IMC departures for private ops? I think there is a danger that some might think it's safe to depart if the weather is within the regulation limits - when it may not be. And if they are too conservative, with no evidence of what the weather actually is, the reality is they will probably be breached in circumstances when it's perfectly safe to do so.
But is this problem really big enough to warrant yet another regulation? How many helo ops are relevant? In the US it's all ATC cleared IFR departures, France doesn't have any corporate ops, in Germany they all take off from airfields, in Oz the weather is always sunny and in Italy..... 😉 So it's mainly UK - with how many IFR twin corporate flying? 100 aircraft? And how many such departure accidents have there been? Accidents on approach or transit in poor weather, yes. But even then the reasons need careful analysis. I really think emphasis should be on training, practice and safety discussion to promote safer flying. And I bet Pprune actually plays a useful role here too!