And before anyone mentions HIV, and how "having the foreskin removed lowers the risk of catching HIV by 60%", you need to know that it's not enough on its own, not relevant to the bulk of infections acquired in the UK (still during sex between men), and of marginal benefit to women*.
But even so, a 60% reduction in risk sounds a lot - it's about what people are hoping for from a vaccine against HIV, should one be developed - and it comes from three randomised control trials in Africa (you circumcise some men, but not others, and see what happens to them over time).
However, it's a relative reduction. The absolute reduction was about 1.8% - over the course of the trials, the risk was about 4.8% (uncut) and 3.0% (cut). The level of complications from serious blood loss and infections, to impotence and loss of the penis was about 1.5%, barely lower than the reduction, and these were circumcisions performed in the best conditions they could arrange.
Just as bad is the fact that the trials were all cut short (sorry! 'terminated early') and this will mask any delaying effect. Imagine that all circumcision did was delay catching HIV by a year, on average. Stopping a three year trial after two years would show a substantial reduction in relative risk - you'd miss all the cut men who caught HIV in the third year!
And it gets worse: in order to maximise what benefit there is, you need to do this in infancy, but there are serious consent issues - you're performing an unnecessary operation with possibly some major complications on someone who can't give consent themselves in the hope that, fifteen or so years later, there might be some benefit. If they turn out to be gay or bisexual, it will be of no benefit. If a medical advance happens in another prevention technology, there may be no benefit.
And if they turn up as a client, you're still going to say 'use a condom'!
* If fewer men have HIV, fewer women will have HIV+ partners, but if the one you're shagging is, circumcision doesn't help you.