You said it, I didn't. But, yes, I think large breasts are the human equivalent of the tail of a male peacock. Small breasts are perfectly functional and actually a lot more practical. Why else should we have developed an appendage that almost
requires a supportive garment? That's just stupid! Just like the tail of a peacock, it's sole purpose is to attract a mate, and it's actually a liability to the bird. Larger breasts, I believe, have an aesthetic value, visually they balance the lower body, and humans are instinctively attracted to balanced features.
Or, if you believe in evolution, maybe the extra fat in those big ol' funbags sustained our ancient ancestors during the Ice Age and the flat chested, natural ectomorphs and their starving offspring almost died out. Maybe if the ectomorphs had married better hunters the majority of women would be 6' tall with 10% bodyfat and supermodels would be 5 x 5s