In the US that debate was resolved by the early 90s based on real world experience,
One of my points exactly. In the EU the increase in commercial air traffic during the past 20 years, has been huge. The LoCo's operate into many 'regional' airports with a density of movements not envisaged when the airspace was created. 20 years ago was the start of easyjet & RYR. They now have 600a/c between them. The spored the growth of many other similar type operators. Regional airfields became airports and massively busy. Some still do not have radar nor ILS. In the EU, only at the LoCo and turbo-prop regional level, there must be >1500 extra a/c in there past 20 years operating into some still very basic airfields. I'm not suggesting all airfields become radar ILS equipped; that requires much capital investment. All I'm suggesting is that the aviation environment has changed rapidly & hugely since the last review of airspace regs. The number of a/c is planned to increase greatly in the next 10 years. The number of affected airfields will also increase hugely. They all want a slice of the pie and some golden eggs. The infrastructure investment is going into terminals and parking space, not into the ATC and NAV facilitates. Meanwhile the regs are still the same as 25 years ago when the skies were a much quieter place.
I suspect there is a lack of awareness & knowledge at the high end. A mid-air will waken everyone up. Sadly, an increase in airmiss reports may not be enough to prompt change.