NVDK ?? I don't want an argument about whether women should breastfeed or not but the evidence is pretty conclusive really, not as you suggest.
[[http://www.ncbi.nlm.nih.gov/books/NBK38337/ This}} is a fantastic review paper I know I keep posting but is very clear - lists where significant differences have been found and where not for developed countries alone.
An extract for example
We screened over 9,000 abstracts. Forty-three primary studies on infant health outcomes, 43 primary studies on maternal health outcomes, and 29 systematic reviews or meta-analyses that covered approximately 400 individual studies were included in this review. We found that a history of breastfeeding was associated with a reduction in the risk of acute otitis media, non-specific gastroenteritis, severe lower respiratory tract infections, atopic dermatitis, asthma (young children), obesity, type 1 and 2 diabetes, childhood leukemia, sudden infant death syndrome (SIDS), and necrotizing enterocolitis
Obviously that is all about risk and definitives just challenging your claim that evidence is inconclusive