Why do we cook our foods?
For digestibility. It's easier on our bodies to digest cooked and thus pre-digested foods. In the world of TCM, cooked food is great for spleen health.
For warmth. 'Tis the season for warming foods. When hot food enters the body, it literally brings the heat with it, warming our gastrointestinal tract.
For increased nutrient content. Believe it or not, but some foods are healthier when cooked. The raw food diet claims that cooking destroys many of the healthy properties within foods (enzymes, vitamins, etc), but some foods, like sweet potatoes, tomatoes, greens (kale, spinach, etc), are actually better for you lightly cooked. The lycopene content it cooked tomatoes is something like 100 times larger than a raw tomato.
For preservation. Cooking delays the inevitable decay of plant and animal tissues. Cooking preserves them a bit longer by preventing the agents that would otherwise cause them to rot (enzymes and bacteria present in the foods cause foods to eventually break-down and spoil, but cooking kills off this bad bacteria and inactivates the enzymes). When food it cooked, it'll last a wee bit longer than the raw variety would have. And if you freeze cooked food, well then it'll last so much longer!
Yes, we all love our raw foods, but as the seasons change, so should our food preparation. Fewer salads and more stews.