I believe it helps blend the spices more evenly and also aids in stuffing the casings. By adding all dry spices and salt probably hardens the mixture. Also probably keeps the sausage more moist. I copied the recipe from a sausage making book. I enjoy both of them.
Also in commercial sausage the govt. allows up to 30% fat (almost 3lbs to 10lbs of meat and by products)and they still add water to their products.

Chuck, you don't have to add a label to my name. Were all friends here. I realize it's always nice to be polite but just jersey will do. And by the way Thank you and Your welcome.