Nipples have a use for men, they are considered sexual organs, as they produce sexual arousing when touched or excited in any way. From one of your sources.
And ever heard of male lactation?
It is not "terrible" at all, but I just know it is untrue. And I studied these things too, and before seeing your articles I had no idea someone actually implies that we are all women until androgen baths our brain/sexual organs.
About the line on the scrotum, well, if you look carefully, the line continues on the penis, and even inside (for uncircumcised men!), on the head. It's just because the human body is (supposed to be) perfectly symetric, why does the... argh, I hate it when I don't know the English word for a biology term... the thing on your back (which goes down from the brain, you know what I mean, I just don't know the English word), have a line? And fetuses, until a certain moment of development, have tails too! What does that tell you?
There are many unused things in our body. Not only in men.
Nipples are a part of the fetal default system as well as the mullerian ducts and wolferian ducts. Lets forget about the word female for a moment. Our species as the probability of producing two products, although mutations are known to take place, two products are typical. The one product we decided to call female. The manufacture created the pro type ( default system to be female) If the signal is not received the pathway will continue female. If the signal from the hormonal influx or cocktail is received then the pathway will alter and we will produce a male. Now there are certain hot spots in our bodies, nipples are one of them, so of coarse men are going to feel sensation in their nipples, this doesn't mean that nipples function in men is for sex. Men feel great pleasure in their anus as well, but I am sure many do not agree with its use, unless it is to defecate. The line that crosses the scrotum and up the penis, if you look at your labia minora and majora that leads up to your clitoris, its the opposite until it closes. This is in the medical journals of development, not talked about much, due to the impact it will give. Oh my God so we all start out as females, men really wouldn't want that fact known, now would we.
I will share a tid bit with you. My once clitoris after hormonal therapy has become a micro penis, it looks exactly as a penis the foreskin the head. We are a byproduct of hormones, as much as you want to deny it. All female body builders that take steroids, there once female bodies changes into male, including hair growth in their face and body, and their clitoris changes into a penis. Just as it happens in the womb when androgen is introduces to the once female fetus. My voice is now the voice of a man, as you can hear on any of my videos, I use to sing soprano and have a very female voice. Case in fact the default is female, introduce androgen, and it will change to male, just as nature intended.
On the opposite coin, a male transforming to female, will take estrogen, and his nipples will become full breast, some get bigger than others depending on their genetic make up. I have seen many female transsexuals well endowed in the breast department after hormone therapy.
In case you did not read the link I provided here is the information that lets you know all fetuses start out as females. You can check the references on the article. Just because you have not learned or read about it before does not mean it isn't true. Remember science and medicine is constantly advancing and changing:
http://www.emedicine.com/ped/topic2789.htm
DEVELOPMENT OF GENDER IDENTITY - USUAL PATTERNS Section 3 of 7
Author Information Definitions Development Of Gender Identity - Usual Patterns Development Of Gender Identity - Unusual Patterns Gender Identity Disorders Of Childhood Summary Of Gender Development In Children Bibliography
Prenatal influences
A child's gender development, meaning maturation of gender identity, clearly begins in the intrauterine stage. Hormone-induced sexual dimorphism in the growing fetus probably plays a primary role. This is apparent in the fact that, most commonly, female sex corresponds with female gender, just as male sex and male gender are commonly linked.
Initially, all human fetuses are female, in that the default pathway is to develop into a female. During the eighth week of gestation, the presence of a Y chromosome and a functional locus for the SRY gene product, also called the testes determining factor (TDF), determines if testicular development will occur. This process converts the inherently female fetus into a male one, as a steadily increasing surge of testosterone is then produced by the testes. Much of the testosterone is converted to dihydrotestosterone, which is the key hormone to virilize the fetus. Along the biochemical pathway, other recently identified gene products likely play an additional role in the masculinization of the fetus.
Further progression toward the eventual male phenotype occurs as antimüllerian hormone is produced, inhibiting the formation of müllerian ducts, which would lead to female genital development. The fetal brain is also affected by this process. The corpus callosum, amygdala, cerebellum, and portions of the preoptic area of the hypothalamus are larger in brains exposed to testosterone. Corresponding parts of the brain are smaller in female, or testosterone-deprived, fetuses. Indeed, in the absence of testosterone, the fetus continues its progression in the female state. Development of the ovaries and the female genital tract is likely triggered by follicle-stimulating hormone (FSH), which is present in both male and female fetuses, but whose effect is masked by the testosterone surge in males.
The gender identity of a fetus, and later an infant, is still incomplete. Yet, current research indicates that because of the expected hormonal exposure secondary to genetic sex, a certain gender bias probably exists in all newborns. This rudimentary gender identity, although incomplete, is an important determinant in gender development. The dimorphism of the brain itself suggests this. Nevertheless, variations may occur when endogenous or exogenous factors create a fetal environment where hormone levels do not follow the genetically determined pattern. The gender bias of these infants may be tilted away from one that correlates with the genotype. Such variations are discussed below.
) and until you can prove that wrong, I will stick by it. 
Just you hear about these folks with a bit of both going on...
