Are there advantages of soaking rice overnight as opposed to only for 30 minutes?
In my experiments with steamed rice and broken steamed rice so far, I haven't found any disadvantage to soaking rice overnight. The rice can be kept on the kitchen counter-top (no need for refrigeration). The rice absorbs a bit of water, but that didn't seem to make any difference in the cooking. It absorbed the usual amount of water (4 cups water for 1 cup rice) when cooked in a pressure cooker.
Given what Jean says about arsenic, it's probably better to soak rice overnight, especially if it is being steamed, rather than boiled.