A huge component of a successful incentive plan is the experience or memory associated with it (Paul Hebert discusses this in a post). Merchandise has the ability to capture this "experiential" effect. For example, it's not the new grill you received but the great cookout with family you were able to experience as a result of having it. Food also provides the centerpiece to a great experiential motivator for employees. They won't (hopefully anyway) be able to have a tangible reminder of that meal. However, they will have the memories associated with that experience, whether it be at a lunchtime potluck or a company-wide recognition dinner.