Historical Context:
In the US, circumcision started in the 1860's from religious movements to discourage the "immoral" practice of masturbation and to reduce sex drive(hygeine or cosmetics are contemporary reasons put forth to support it). It gained momentum and in the 1930's up to 80% of infants were circumsized. This remained until the 1970's when medical science deemed it unncessary. Rates declined and today 60%-65% of infants in the US are circumsized (well between 1987-1995 this was the rate).
Medical Context:
There is no real medical benefits of circumcision versus non-circumcision. While it has been shown that circumcized males have less instances of Urinary Tract Infection, Penile Cancer, and susceptibility to HIV, such benefits either statistically insignificant or are influenced by one's lifestyle choices (in studies cited, uncircumcized males slept with greater numbers of women thereby increasing risk) and are mitigated by the increased risks posed by circumcision such as death, complete or partial amputation, and infection. That said, no national or international medical institution advocates circumcision. However, studies have shown that medical arguments do not change parent's decisions on circumcision. And don't forget, there are times when circumcision is a medical necessity in an infant and should be done without hesitation.
Social Context:
Believing that a cut or uncut penis is 'ugly' is a learned response based on cultural norms and expectations. Tradition is power. What should override cosmetic concerns are qusetions of equal rights, the right to self determinism, to anonomy, and the ability of the circumsized infant to be able to enjoy sexual experiences to the fullest as an adult. It is illegal to practice female circumcision but not male circumcision for social reasons, and not because it has any actual legal basis.
Sexual Context:
10%-15% of males in the world are cut. Most women and cut men can hardly tell the difference between a cut and uncut erect penis (much of the porn online now features European male models almost all of which are uncut and nobody notices). With just over half of infants still being cut in the US, the issue of being ostracized by schoolmates is a weak one. Some people will prefer cut over uncut or vice versa. In the end it's really a non-issue assuming one practices proper hygeine.
http://www.ama-assn.org/ama/pub/category/13585.html
http://www.circumcision.org/circumcisionpolicy2004.htm
http://www.ncfm.org/circumcisionfactsheet.htm