A new study seems to indicate that circumcision is hugely beneficial in terms of protecting against HIV infection. From the San Francisco Chronicle:
The study's preliminary results, disclosed Tuesday by the Wall Street Journal, showed that circumcision reduced the risk of contracting HIV by 70 percent -- a level of protection far better than the 30 percent risk reduction set as a target for an AIDS vaccine.Note that I am not claiming that this is the reason for the commandment. It is just, evidently, an amazing benefit.