Not at all, I know what you are trying to say. I don't know if I can say it clearly either.
I think the reason men find breasts attractive anyway varies between men (eg certain men find particular sizes more appealing than others), but it's probably initially that a (reasonably) well-endowed woman would make for a decent milk-providing mother. Same with the hips. Not that I'm an expert in the mechanics of it but I understand that a wider pelvis makes it easier to give birth (relatively speaking, at least...).
Anyway, the book is, at breast, suffering from the same problem. That men find breasts attractive is incidental to their original purpose.