Maybe not food is vastly deflated in value, If people knew the time needed and benefits of organic food more the price of real food would double and more people would have re-thought the move from farm to city.
There is a sinister interest in the de-valueing of food i think.
Assuming that's true for the sake of argument, could we return to a labour-intensive agrarian economy like we had in the medieval period? How could that happen? We'd have to cut population a lot too - how could that happen?
It might be a more sustainable system, but I don't see how we could get from here to there even if that system did work. We don't know that it would, so it would be a big gamble. It's something I'd play with in a god game, where I could just start over if it didn't work.
EDIT: Even "medieval period" is a bit much. The move from farm to city that you refer to had already started in England by the late medieval period due to increased efficiency in farming and the subsequent reduction in labour required.