Scientific American reports that cats cannot taste sweets, which is why they are only really interested in meat. As a diabetic and meat lover, I can quite relate to this.
One issue that the article points out is that not only can they not taste sweetness, but also lack the ability to properly handle it in the body. Putting cereals into cat food, therefore, may be a less than good idea. As the fast food industry works diligently to ensure that every human on the planet is diabetic (thus expanding the market for their pals in the pharmaceutical industry) it would appear that the pet food industry is dancing to the same tune.