how often does it go wrong? and how does that number compare to numbers for yeast infections and other issues stemming from non snipped? because it seems to me that there is no real compelling evidence on way or another.
A "less than fully functional member" ALWAYS results, I mean by definition. You are excising parts here. Not only do you lose the majority of nerve ends, the loss of the foreskin results in scarifiication of what's left. Discussion of "complications" is moving the goalposts.
If you circumcised your kid, you already chose to radically change his penis and affect his future sex life. Best case scenario is he and his future wife are content with what they are missing and convince themselves that it's ok.
Circumcision is the only prophylactic surgery still performed in the civilized world. Maybe it could be justified if there was truly life-threatening concerns, but there aren't. My friend's kid got a UTI, and the prescription was "make him drink lots of water". This leads me to conclude that the motivation is mostly cosmetic, and unfortunately for the victim utterly irreversible.