It's a real shame.
I think GA is paying the price for being too tight to pay £15-£20 to land, and to enable somebody to run an airfield on a proper commercial basis (by that I mean to not lose so much money that they sell out to developers at the drop of a hat).
That is obviously a simplistic explanation and a more fuller one lies in the difficulty of getting Planning to establish a brand new GA airfield somewhere.
If new airfields could be established, with rateable values appropriate to them being airfields and not trading estates, we could allow most of the existing ones to shut down, hand them over to the property sharks who are always circling anyway, and start again with new facilities, with proper hangarage available, located away from population centres so they don't draw complaints, etc.