> "The risk of developing either diarrhea or ear infection increased as the amount of breast milk an infant received decreased."
Yes, but by less than a factor of 2 for a digestive condition that, while a killer in the developing world, is at most an inconvenience in the developed world.
> "The crude incidence density ratio (IDR) revealed a protective effect of breast-feeding on respiratory illnesses (IDR=0.66; 95% confidence interval (CI), 0.52 to 0.83), on gastrointestinal illnesses (IDR=0.53; 95% CI, 0.27 to 1.04) and on all illnesses (IDR=0.67; 95% CI, 0.54 to 0.82)."
It's interesting that you leave out this part of the text: "The protective effect of breast-feeding on respiratory illnesses persisted even after adjustment for age of the infant, socioeconomic class, maternal age, and cigarette consumption (adjusted IDR = 0.78; 95% CI, 0.61 to 1.00)." There is no reason to ever report IDRs not adjusted for socioeconomic class, maternal age, and cigarette consumption, because breastfeeding rates are not uniform among these groups. So the first set of numbers is meaningless. An IDR of 0.78 is not a big benefit. It means that if something happens to bottle fed infants 10% of the time, it'll happen to breastfed infants about 8% of the time. And remember, this is just the first six months of life--the available studies show these sorts of effects diminishing as the child gets older.
> "Infants exclusively breastfed ‘at discharge from the obstetric hospital’ (odds ratio [OR]=0.52, 95% confidence interval (CI):0.35–0.71) and during the last 2 days (OR=0.65, 95% Cl:0.46–0.91) had a significantly lower risk of SIDS than infants not breastfed after controlling for potential confounders."
The number of babies that die of SIDS each year in the U.S. is about 2,500 out of 4,000,000+ births each year. With an OR of 0.65, we're talking about a roughly 0.075% risk versus a 0.050% risk. For comparison, your child has a 1.2% chance of ever dying in a car accident.
> "Exclusive breastfeeding (EBF) may substantially reduce breastfeeding-associated HIV transmission."
This is the only one of the lot that's actually worth talking about. We're talking about OR's of 2.5-4 for something that has an overall incidence rate of 12.1%. So if you're HIV positive, exclusively breastfeeding can substantially reduce your chances of transmitting the virus to your child.
Your Bangladesh (my home country!) example is irrelevant to people in the developed world. The water in Bangladesh is full of arsenic and disease. Of course breastfed infants, who don't drink the water, are going to be much healthier than bottle fed infants who do.