Another great article. It’s really a shame there isn’t more info on this topic. I learned only through experience about the astonishing capabilities of the female nipple and I think some of my earliest encounters would have been better for all concerned if I’d been more aware of their potential.
As for male nipples, there’s no evolutionary puzzle: male & female bodies derive from the same basic body plan, with various parts adapted accordingly. Male nipples are just vestigial and there’s never been any selection pressure to reduce them further.