I am all for keeping the Williamson Act but I think the discussion should include the concept that reduced property taxes for farms are "fair" because on an acre by acre basis farms require less county services than cities and subdivisions. They require less in way of roads, fire protection, police protection, schools, etc.(100 acres of farm usually has just one family of kids for schools. While 100 acres in a city can have hundreds of houses with many more kids.) So the reduced property taxes for Williamson Act contracts can be justified not only to conserve farmland - but they can be justified to urban residents as a fair allocation of county costs.
So removing the Williamson Act provisions takes us back to a point in time where farms receiving very little in county services (proportion to their size and value) are subsidizing urban areas. That does not seem right to me. And yes, I know this happens all the time. When I lived in the city I paid my property taxes and never put a kid in school. Happy to do it. But I also had a police department nearby, a paid fire department, and roads that were fixed on a regular basis.
And in case any of you accuse me of being self serving - yes, my property is in the Williamson Act but the difference between that assessment and my Prop 13 calculated taxes is so little that the Williamson Act is of no value to me personally. In fact I would like to be out of it - I don't like some of the restrictions. But losing the Williamson Act will hurt my neighbors tremendously and in some cases put them out of business. At the very least the price they charge for their produce would have to go up. Others - who sell into markets where they don't control their prices (like Walnuts)- will be hurting pretty badly.