Perhaps I have not adequately addressed this question. Why soup? Well the humble soup is so versatile that's why. What other food item can be eaten as an appetizer, entree, in between meals and dessert? I can't think of any. Off the top of my head, I can list ten reasons why soup is awesome and we need to pay homage to it.
1) What else are you going to do with left over bones/carcasses, giblets, necks, feet, shells etc.
2) Keeps you warm and toasty in the winter, and refreshes you in the summer.
3) Can help maintain body weight (as long as you avoid the creme of (insert soup name) or veloutés if eaten as main meal or before the meal (so you fill up on low cal stuff first)
4) A way to get those finicky carnivores to obtain some vegetable matter
5) A way to get those finicky vegetarians to consume some sort of protein, in the form of legumes
6) Can be whipped up in as little as 20 minutes, tastes great when re-heated, and can be frozen
7) A great way to use left over hodge podge of ingredients in the fridge and cupboard.
8) Pairs great with hot crusty bread, or yummy toasted bagel and cream cheese
9) An excuse to use those kitchen tools you just had to have, a.k.a crock pot, blender, food processor
10) You feel less guilty eating the cheesecake for dessert. After all, it's only soup right?