Crab, fully acknowledge the issue that you're describing but the requirements for separation are sourced from ICAO and have been reinforced in recent years by research undertaken by the FAA and EUROCONTROL; albeit that research focused on fixed wing.
The CAA did some work on RW wake turbulence a few years ago (which resulted in a minor amendment to the ICAO materials, I think a note was added) but it focused on RW AS generates of wake, not how they react to wake. I believe that there was a plan to do some (UK) research on this aspect a few years ago but the funding application fell through.