It is done for health reasons. That forskin traps many bacteria and viruses that thrive in that setting. The odor alone indicates that. But the most serious reasons go much further than the foul odor. It also contains the virus that causes cervical cancer in the women.(HPV) It poses a risk to the female sex parters who are exposed to it. Higher rates of HIV and communical diseases such as chlamydia, gonorrhea and syphilis are among those who are not circumcised and women who have sex partners who are not circumcised. When circumcision is done on an infant it heals almost instantly. Many times if it is not done then later the boy or man will develope an infection that requires it to be done and that is very painful and takes longer to heal. When a boy who is not circumcised reaches puberty, he has an obligation to keep the area under that skin clean. In addition to all of this, the Bible instructs parents to circumcice their male infants.
Got a little off topic didn't we?
Re-read Paul's admonition about a believer taking circumcision as the most important showing of obedience...and how those who believe that are misguided.
My home entertainment system is circumcised, but I don't have any urge to show you, nor is that my Ace-in-the-Hole plan for salvation.