Why isn't our Intelligent Designer's regulations on male circumcision to help control sexually transmitted diseases based on His working ?

You seem to presume that the reason for circumcision is to prevent the spread of infections. One thing it would definitely do is reduce the risk of penile cancer and probably HPV infection, but we don't know if that's why God instituted that mitzvah any more than kashrut was commanded connected to health. Ours is not to reason why, and it's a hostage to fortune when we do.

"For (((IN))) Christ Jesus [aka Spirit; II Cor 5:16] neither circumcision nor uncircumcision avails anything, but a new creation" (Galatians 5:16).

"But he is a Jew, which is one inwardly; and circumcision is that of the heart, in the spirit, and not in the letter; whose praise is not of men, but of God" (Romans 2:29).

"Probably not many Bible scholars or scientists are aware that Daniel—the same Daniel who was cast into the lion's den—was also a scientist. A scientist may be defined as one who utilizes the scientific method as a means of testing hypotheses. Scientists are also trained in research methodology. Daniel, therefore, can be classified as a scientist both by training and practice. In Chapter I of his book, Daniel gives the account of his use of classical experimental design—a technique to control variables that might bias a scientific research project—in order to acquire knowledge and test a hypothesis."

Therefore since scientist have conclude that circumcision can be an advantage to health problems and God said "Neither circumcision or uncircumcision avails anything" 

GOD has spoken!

It's a man's decision for it is of the flesh which is not of the spirit!

Why didn't your "Intelligent Designer" just design its creation without a foreskin?

Seems it would have been the more intelligent thing to do.