Just like grains, nuts contain phytic acid which is part of their defense mechanism to avoid predators so that they can grow to their full maturity. Often, you may find some bits of nuts in your stools because phytic acid works against easy digestion of the nuts. Soaking helps to get rid of phytic acid and neutralizing enzyme inhibitors enabling easy digestion and elevating absorption of vitamins and other nutrients in the nuts.
The peels are more easily removable, once you soak nuts in hot water. Adding a little salt while soaking will help neutralize the enzymes. It also helps remove dust residue and tannins.