It's no advantage to have a long penis. Typically, long penises are not very wide. Therefore they're less rigid. And that's bad for sexual performance. And that's more likely to be pleasurable.
Women have very few nerve endings in the vagina.
After all, when women buy dildos, they tend to select medium to smaller sized units. It was a turn-on to look at it, and an ego trip that a man that huge was my partner. But the actual feeling inside me didn't give me one hundredth of the pleasure that my more modestly sized present partner does. While the size of a man's penis does create different sensations, it is the relationship I have with the man who is attached to the penis that determines what those sensations add up to.