I think that MJ may have hit the nail on the head. The original concept of ATSOCAS was to ensure consistent service provision between all ATS providers. Part of the problem is that this doesn't appear to be happening. I know that ATS provision is common across some of the Class G ATS providers, but this doesn't appear to be a level playing field. That's wrong.
MJ also hints towards the funding model for UK ATS in Class G airspace. Aside from the protection of their own aerodrome's IFR traffic, what real imperative is there for civilian ATS providers to provide the UK FIS to transiting traffic, irrespective of the flight conditions of that traffic? Sadly none, which means that the user stops trying to use it, as MJ highlights.
MJ, I only hope that if the CAA runs a consultation on this issue within the next few years, you choose to comment on it to ensure that these thoughts and experiences are captured.