If our cultural priorities allow for landfilling or incineration of organics, we are keeping valuable organics away from the topsoil. If this practice is allowed to continue, then our food supply will become increasingly dependent on non renewable resources. Cost is not everything when it comes to environmental priorities. Consider the following. Raw sewage in the river is cheaper than primary treatment.
Primary treatment is cheaper than secondary treatment.
Secondary is cheaper than tertiary. People just factor the sewer bill into the tax base and stop thinking about it. Open dumping of garbage in the back yard, at the end of the alley, or in swamps is cheaper than a town dump. Sanitary landfills are more expensive than town dumps. Composting is often more expensive than landfilling, and so forth.