The foreskin is there for a reason. It protects a very sensitive part of the body: the glans of the penis. It is the male equivalent of the hood of the clitoris. The head of a cut cock is subjected to all sorts of abrasion from which uncut ones are protected. It looses sensitivity over time.
The practice of routinely circumcising boys began in late 19th century Britain, for the perverse reason that it was thought the foreskin encouraged young Empire builders to engage in morally degrading acts of self-gratification

America soon followed suit. No longer in possession of an empire, the Brits have long since come to their senses on this matter. One only wishes that the USA would, too
Aside: masturbation is extremely healthy, especially if you start at the onset of puberty. Adolescent masturbation is believed to be protective against prostate cancer in the same way that early pregnancy protects against breast cancer: both encourage the maturation of the tissue before it has had time to accumulate mutations that can lead to cancers.
One bad note: the area under the foreskin can harbor Human Papilloma virus (HPV), making uncut men a reservoir for this pathogen that causes cancer of the cervix in women. However, the extent to which this contributes to the spread of this disease is questionable, as the rate of abnormal PAP smears in Europe, where most men are uncircumcised, is about the same as in America, where most men are.
Rarely, HPV infection can lead to cancer of the penis (yikes!). To the extent that this rare condition is a problem, cut guys are much less at risk.
The good news is that an HPV vaccine should be out shortly. This should irradicate cervical cancer, as well as those rare incidences of penis cancer. It should also have a profound impact on aggressive cancers, where HPV infection is considered to be the major contributory factor (any 'small cell' cancer)
Wouldn't you know: some Christian groups are against routinely vaccinating people against HPV. They feel it will promote promiscuity
Returning to the topic at hand, I wish I had my foreskin, for practical, personal, and cosmetic reasons. And don't let anyone tell you it doesn't hurt the baby. Most of those little guys scream like mad when they get snipped. What a way to enter the world
