Gastrointestinal Illness: At least 400 infants die annually in the US from diarrheal disease; an estimated 250-300 of these deaths are attributed to not being breastfed.
Respiratory Illness: Between 500 and 600 infants die annually in the US from acute respiratory disease attributed to not being breastfed. The risk of fatal or nonfatal respiratory infections is two- to five-fold higher among formula fed infants.
Otitis Media: Ear infections occur more frequently in infants who are not breastfed.
Bacteremia and Meningitis: There is a fourfold higher risk of bacteremia and meningitis among babies who are not breast-fed.
Juvenile Diabetes: More than 100 studies indicate that breast-feeding can delay or prevent the onset of diabetes in children.
Malignant Lymphomas: A six- to eight-fold increase in the risk for lymphomas among children younger than 15 years has been found in children who were not breastfed for at least 6 months.
Breast Cancer: Having been breastfed as a child reduces breast cancer risk in women over 40 by more than 25%.

The emotional damage from not being breastfed is quite real, as well.

Compare the hundreds of babies who die annually from "not being breastfed," and those who develop diabetes, cancer, or other conditions later for the same reason, with this table showing the numbers of children under 10 who die from accidents in the U.S. annually:

Causes and Numbers of Accidental Deaths of Children Under Age 10 (1997)

1. Motor vehicle ------------- 1,783
2. Traffic ------------------- 1,626
3. Drowning ------------------   750
4. Suffocation ---------------   577
5. Residential fires ---------   570
6. Struck by or on something -    89
7. Falls ---------------------    87
8. Cycling -------------------    78
9. Poisoning -----------------    58
10. Firearms -----------------    48