True, there are some mods that help with this though. Try tweakerlord, it increases both the max food capacity as the possible food production.
Be warned though, only a stable economy in combination with a larger storage can provide you an actual permanent solution. Increasing production is a temporary fix but will stop having effect with higher prosperity. As the bonus in production doesn't scale with prosperity.
Also this will increase the general amount of militia and garisson in the average town/castle. I do like this part. Though increasing food stock should also have this effect in locations where the economy is stable. Having a more realistic effect and still making economic sabotage a viable option.