Legalapproach
I take your point. "Nightmare" is too strong a word. But I have a perception that many accidents are workload-related. It's never the case that avoidance of a particular hazard itself gets the pilot into trouble, but rather it's the straw that breaks the camel's back.
It's all very well to talk about the 'inconvenience of having to plan around', but most plans have to be dynamic. Weather and ATC conspire against a pilot to ensure that even the best battle plans never survive first contact with the enemy. If you can manage to fly IFR from East Anglia to Bristol out of ground contact on a convective day with serious weather around, and be 100% confident that you can give all the hazards along the way due consideration, then I'll happily admit that you're a better pilot than me.
I fully support the cause of all airspace users, and I firmly believe that we need to learn to coexist. There does however, need to be a balance between the rights and responsibilities of the various parties. The DZ notification arrangement in place for the last few years has done a great deal for that balance.