One of the problems is airspace structure, since most of airspace in Europe is controlled above 1000ft AGL / 3000ft MSL and many (if not most) controllers don't like to see "crazy VFR traffic" in their airspace, so the only option for non-IR rated pilots (or aircraft not IFR equipped) is to fly below inversion level and it's nearly impossible to spot any traffic when flying in mist with sun at 12 o'clock.
Sorry, I'm having some difficulty understanding you - why should pilots feel the need to fly in Golf Airspace? I've flown across Germany, Austria, Hungary, Slovakia and, with weather like yesterday, airspace was not an issue - I usually stick in Echo which, if we remember, is controlled airspace but there is NO requirement to be listening to the FIS for VFR or to get a clearance (clearance only required for IFR); in Germany, Echo goes from between 1000, 1700 or 2500AGL up to FL100 so I could quite happily bimble around FL 55 - 95 without any problems, unless other airspaces get in the way. The only requirements are flight visibility 8km or more, separation of 1500m horizontal and 1000 feet vertical from clouds. From my part though, I will always contact the controllers who have always been more than willing to provide traffic service even though yesterday was fairly hectic - the poor controller certainly earned her pay - so I can't really agree when you say that the controllers don't want "crazy vfr" traffic in their airspace.
Concerning the inversion, I also don't see an issue flying above it where the visibility is excellent, irrespective of whether the plane is IFR equipped, pilot IR rated or otherwise, then ducking below the inversion when nearing the destination - or how does anyone else see this? In such circumstances I'll keep listening to the FIS as long as possible in case of traffic advisories, tune COM2 to the airfield frequency and listen in from about 10 minutes out just to judge how many planes are in the circuit and their positions / intentions and then drop down into the circuit as late as possible.....