The funny thing is that eating rice isn't even that old of a tradition, and neither is eating it in polished, white form. White rice only became ubiquitous when milling technology improved, and spoilage of the oils in brown rice became a concern for storage.

> Despite its long history in Japan rice was, for a long time, a food reserved for the warriors and the nobility. It was consumed by the majority of the population only from the seventeenth century onwards, not becoming the basis of Japanese food until the early twentieth century

https://www.japan-experience.com/to-know/chopsticks-at-the-r...

> A disproportionate share of the rice crop was therefore consumed in the cities and by the political and economic elite, while the diet of much of the rural population continued to depend on the availability of a range of other grains – wheat, millet, barley, etc. – together with vegetables, fruit, pulses and occasional fish or game, grown at home or collected in the locality.

https://www.tandfonline.com/doi/abs/10.1080/0955580070133003...