I'm certain it's mainly down to demographics and the labour market. Back in the day when we were an industrial nation guys worked at the factory or forge all week and their wives largely stayed at home doing an equally important job. They also realised that their other half needed some fresh air in his lungs at the weekend. In my old area the league teams were largely the big employers and competition was fierce.
But now that both halves need to work to have a decent standard of living, and employers tend to have smaller workforces, there just aren't the numbers. Add to that the disappearance of works sports and social clubs, some of which had county standard grounds (I bet Mr Aldred might have played at a few) and there is your answer. The same thing happened with match angling, which, similar to cricket, is the best part of a day gone from the weekend. Nowadays our fresh air comes from visits to garden centres or doing the weekly shop. It's a clock that ain't ever going to turn back.