The variety of colors and shapes are more of an asthetic to the human buyer than to your rabbit. Again, fresh vegetables, restricted high fiber pellets, and unlimited hay are healthier and easier on your budget. These are mixes which are made of seeds and grains. They are made of carbohydrate and fat-rich seeds and grains such as oats, milo, corn, peas, sunflower seeds, potatoes, peanuts, puffed corn, cornflakes, popcorn, and dried fruits. In reality, a diet of vegetables, hay and restricted pellets provides all the nutrients and energy your house rabbit needs.
Seeds are high in fat and are important for wintering animals.
These seeds and grains are also rich in starches. While some of this starch is digested in the small intestine, much of it is not accessible until it reaches the cecum. While this is true, it is far safer and cheaper to satisfy that urge with baskets, untreated wood, and cardboard boxes. These are grain products which may be supplemented with dehydrated vegetables, and shaped into a form which mimics a vegetable product. There is no advantage to feeding these over the real vegetable.