I've stated many times here on GC that I am NOT circumcised.
One of the reasons I view "circumcision" to be worse than rape is because I would literally rather be raped up the ass than have the most pleasurable part of my penis cut off.
You're asking "why" when many of us, including myself, have explained again and again why genital mutilation is such a terrible thing. As an example, see my "I have a complex" reply to Eeyore.
Many men feel traumatized from having had their genitals mutilated, there are even men who commit suicide because of this. Babies often die, or have botchings, from these "circumcisions".
That's just the start of the real scope of it. But you're right... it's a perverted "fixation" we have. There is nothing wrong with a society that believes giving children sexual pleasure is evil, but sexually assaulting them with knives is alright.