Why Do You Cut Off The Foreskin, Taking Away More

why do you cut off the foreskin, taking away more than 20,000 nerves and the sexual functionality of the foreskin? One of my friends is a nurse, is pro circumcision, and even SHE doesn't believe that circumcision reduces the chance of sexually transmitted diseases.
There is a 60% reduction figure out there, but here is why that is flawed.
When the tests about wether circumcision prevented sexually transmitted diseases we're conducted, the main one chosen was the study in Africa.
The researchers took a control group of intact men, and then compared the amount of that group that got sexually transmitted diseases to that of the other group, which got their genitals mutilated, AKA circumcised.
The thing about African circumcision is that, to give the penis time to heal, they have a tradition of taking three months of abstinence from sex.
The study was conducted during that period, and was concluded right as the three months would have been up.
Convenient, isn't it?
let me ask again, do you still think circumcision is an okay surgery, and if so, why?
Honest answer please, I want to hear this.