As one currently suffering from a badly burnt calf as a result of wearing shorts and no socks with my sandals, I know why I generally wear shorts and socks. Why my feet did not burn as well, I don't know. [Yes, I did apply SPF 35 lotion. It failed me.]

I generally wear socks and sandals for the comfort. Now I will also wear them for the protection, even when I am in a canoe.