The doctor is saying about the female sex organs the same thing you're saying about male nipples.....only we know the female orgasm isn't under-developed or vestigial, so it's entirely logical to assume the doctor doesn't have the slightest idea at all of what she's talking about.
The "just for fun" aspect of female nipples is learned, you know. There's no evolutionary need for them to be pleasurable. I would argue that if mens nipples were emotionally thought of as sensual, they would be sensual.
It's all up here >>>points to brain<<<