I have asked this same question to bbq fanatics and Chefs alike. What I know is salt, although not incredibly necessary, has a dual purpose.
Salt will boost the flavor of the blend you are making but be careful not to go crazy with it as it will be more salty than tasty. Also salt aids in holding in the moisture of the meat and keeping it succulent. There is a scientific reason that has to do with restricting capillaries or something of the sort. I cannot find the actual letter that explains it but in a nutshell it aids in keeping the liquids from flowing out while cooking. Hope this is helpful.
What if the the Hokey Pokey IS what it is all about?