Hungry dogs wait patiently while watching the pack leader's face for permission to begin dinner.
Once again, I will emphasize the importance of the "Stay" command. Many, many dog owners and trainers believe the "Come" command is the most important of lessons for your dog. I believe "Stay" has more overall value for your dog.
If your dog assimilates the self-restraint involved with learning to stay, he/she is better able to handle the stress of the dog world. Stress such as: being left alone at home, not being allowed to eat all those delicious items off the street, not being allowed to bark insults at other dogs on the street, not being allowed to chew on furniture, and much, much more.
After all, humans learn restraint and use it everyday to handle situations we don't like. Humans have to "stay" in line at the store. Humans wait for food to be prepared even when ravenously hungry. Humans don't attack or shove people who get in their way. We learned this when we were young. When we were very young and wanted something, we just tried to grab it.
When your dog learns to stay or wait, she/he also learns how to be patient. This patience helps the dog from becoming overly frustrated and stressed when not being able to eat or do something he/she wants. Your dog does not want you to leave whenever you go out. But if they have developed patience, they are better able to hunker down and wait for your return (as opposed to freaking out for hours while you are gone).
"Come" is a lovely command which I also taught my dogs. However, would you prefer a neurotic dog who comes when called or a happy dog who sometimes ignores you. (You can actually have a happy dog who always comes, but I am attempting to emphasize a point).
One of the best opportunities to practice "stay" is at feeding time.
Another wonderful benefit to "stay"...I can go inside to get my morning coffee (No dogs allowed!)