Interacting with people is indeed needed in all the business, but it is must in fast food business. The business needs not to just convince people about the quality but need to woo them.
One benefit available to celebrities is they have a large fan following, making the marketing task easy for them. That is the reason we had seen grand opening of Wahlburgers:
But the owners are definitely serious about the business and hence involving the customers in the business, to get know their choices. One such campaign they run on FaceBook and it gave the results too.