It is desirable that countries should specialize in growing food types that they can most efficiently produce for the world at the cheapest price.
Protectionist policies in agriculture reduce economic efficiency, destabilize world markets, exacerbate tensions between industrialized countries, and threaten progress towards further multilateral trade liberalization. The advantages of lower consumer prices and improved trading positions for the third world far outweigh the disadvantages of removing support for currently subsidized farmers in rich countries. Why should Japan grow rice at a huge loss financed by the taxpayer when other Asian producers like North Vietnam and Thailand would be only too willing to supply more cheaply ? The argument that a country needs to be self-sufficient in food for strategic purposes is answered by stockpiling.
This model of economic activity has little correspondence with reality. Specialized food production for export has meant that small-scale food producers (and in many cases even small countries) have been marginalized in a variety of ways and all the harvest of specialization has been reaped not by the producers themselves, but by a limited number of big players who have been able to gain control over the global food chain.