Ever wrongly assumed something when visiting unfamiliar restaurants (especially ethnic restaurants)?
In many Chinese restaurants, it is customary to offer valued patrons a bowl of complimentary soup in the beginning of a meal. Often enough, this complimentary (free of charge) soup include chicken feet. Many people may think "Oh my, they just put in a bunch of left over chicken feet and stuffs in this *free* soup". I certain thought that was the case in the very beginning. When in fact, chicken feet actually cost more than chick thigh, legs and many other parts. The reason the restaurants use chicken feet is because of its high gelatin, not because the feet are left over or cheap.
They use chicken feet because they like you. :)