I am a regular flyer at airfields with full ATC, FISOs, and radio. I think that one of the main issues is that a lot of pilots are unaware of the kind of service that they are receiving, and that is a pilot training matter.
Incidently, at White Waltham where I fly from there is no ATC service, but a radio service, the system works safely and efficiently and the circuit discipline is excellent because pilots safety is in their own hands rather that ATC.
I also wonder whether the smaller airfields would be able or willing to finance a full ATC service?