While the question centers on religious traditions, the facts are (for the U.S. at least) that federal data from 1999 showed hospital circumcision rates of 81 percent in the Midwest, 66 percent in the Northeast, 64 percent in the South and 37 percent in the West of the U.S. (Source: msnbc.com).
Additionally, (Source; ibid.) "... the National Institutes of Health published a surprising report in The Lancet showing that circumcision reduced a man's risk of contracting HIV, the AIDS virus, through heterosexual sex by 51 to 60 percent compared with men who were not circumcised. The findings were based on two trials in Africa involving more than 7,500 men and were halted early because the preliminary results were so striking."
Another study , published in the journal Pediatrics in November, 2000, followed 510 New Zealand newborns until age 25 and found that circumcision cut the risk of contracting sexually transmitted diseases by about half.
So, while the religious beliefs of some adherents require the operation, it can't be denied that evidence suggests, strongly, that other benefits are derived...