It will encourage people to have more sex without effective protection (ie. condoms) if they falsely believe that circumcision already covers them — particularly women seem to believe in circumcision as some sort of wonder weapon against esp. HPV. Add a bit of alcohol and the bareback with the handsome circumcised stranger recently met doesn't appear just that dangerous anymore.

Same thing (risk compensation) happens in Africa with circumcision against HIV: Whatever little benefit there may be for men is eaten up by enough mislead behavior of those falsely convinced to now somehow wear an "invisible condom".

See this video with an attempted ranking.

About its purpose in Judaism, here's what Maimonides wrote:

"[W]ith regard to circumcision, one of the reasons for it is, in my opinion, the wish to bring about a decrease in sexual intercourse and a weakening of the organ in question, so that this activity be diminished and the organ be in as quiet a state as possible. [...] How can natural things be defective so that they need to be perfected from outside, all the more because we know how useful the foreskin is for that member? [...] The bodily pain caused to that member is the real purpose of circumcision. [...] The Sages, may their memory be blessed, have explicitly stated: "It is hard for a woman with whom an uncircumcised man has had sexual intercourse to separate from him." In my opinion this is the strongest of the reasons for circumcision."

The words of Kellogg, the man behind much of its popularization in the US:

"A remedy which is almost always successful in small boys is circumcision, especially when there is any degree of phimosis. The operation should be performed by a surgeon without administering an anæsthetic, as the brief pain attending the operation will have a salutary effect upon the mind, especially if it be connected with the idea of punishment... In females, the author has found the application of pure carbolic acid to the clitoris an excellent means of allaying the abnormal excitement."

Video with an attempted ranking: http://www.youtube.com/watch?v=98f3IavuEgQ

The stark Type III (infibulation) makes up about 15% of worldwide FGM.

Less invasive forms of FGM that are comparable to male circumcision — the so called "Mild Sunnah", for instance — are banned regardless, and rightly so.

"[W]ith regard to circumcision, one of the reasons for it is, in my opinion, the wish to bring about a decrease in sexual intercourse and a weakening of the organ in question, so that this activity be diminished and the organ be in as quiet a state as possible. [] How can natural things be defective so that they need to be perfected from outside, all the more because we know how useful the foreskin is for that member? [] The Sages, may their memory be blessed, have explicitly stated: "It is hard for a woman with whom an uncircumcised man has had sexual intercourse to separate from him." In my opinion this is the strongest of the reasons for circumcision."

http://books.google.com/books?id=SF6fbjNe0yYC&pg=PA65&lpg=PA65&dq=%22decrease+in+sexual+intercourse+and+a+weakening+of+the+organ+in+question%22

Nowadays vaccinations for both genders are available against most of its strains, and circumcision won't replace the importance of proper sexual hygiene, either. You might as well argue that a false sense of protection leads men to more risky behavior.

There already have been two longer replies to the AAP's statement:

http://www.circumcision.org/aap.htm
http://www.doctorsopposingcircumcision.org/pdf/2012-08-26A_Commentary.pdf

Their most important points:

1. The AAP chose to overblow purported benefits by cherry-picking studies and advertising their results past their proportionality, misleading the public with doublespeak of "pro" while admitting circumcision still does not qualify as routine amputation.

2. The AAP omitted both contradicting studies and objections to those it used, such as to the three WHO HIV studies.

3. The AAP omitted any discussion of the foreskin's functionality and notice of possible complications after circumcision (incl. death, an estimated 117 boys in the US per year).

One could think they felt the heat as one national agency resp. adviser after another rejected or even condemned infant circumcision.

The three WHO Africa studies did not survive review:

http://blog.practicalethics.ox.ac.uk/2012/05/when-bad-science-kills-or-how-to-spread-aids/

http://www.publichealthinafrica.org/index.php/jphia/article/view/jphia.2011.e4/html_9

Not application:

http://www.theafricareport.com/index.php/20120711501815186/southern-africa/zimbabwe-concern-over-high-hiv-rates-among-circumcised-males-501815186.html

http://www.measuredhs.com/pubs/pdf/CR22/CR22.pdf (botton of p135)

Also, infection of men by heterosexual sex is the least important transmission vector in the West, nor does circumcision apparently influence the infection of women by men:

http://www.thelancet.com/journals/lancet/article/PIIS0140-6736(09)60998-3/abstract

Besides, how rational is it to tell men that they must be circumcised to prevent HIV, but afterwards they still need condoms to be protected from STDs?