I agree it should not be done unnecessarily. I've hooked up with plenty of men in my lifetime and have seen some grotesque circumcisions.
The worst botched ones I've seen are when the skin bridges to the head or when the circumcision was done too tight (and causes issues when erect). More commonly, I've seen some pretty gnarly scar tissue along the shaft, but that seems to be less problematic. I am curious if folks with botched circumcisions are still supportive of it, since it's so ingrained in their culture.