Why should you not put tomatoes in the refrigerator?
When you buy a tomato, it is still alive. So is the broccoli, the lettuce, and the other fruits and vegetables in your kitchen. A nice, fresh salad is one of the few foods that we eat while it is still alive. For most of these vegetables, putting them in the refrigerator just slows them down, causing them to die slower, but for tomatoes, along with avocados and bananas, the cold of your refrigerator speeds up their death. In tomatoes, this damage causes all sorts of chemical changes. Flavor compounds, such as Z-3-Dexanol shut down. These chemical changes also change the texture of the tomato, giving it a granular texture.
This is only true for living tomatoes. Once you kill them by cooking, the refrigerator is the perfect place for them, as the cold also slows down bacteria that can cause foods to spoil.