As a former body piercer for more than a decade, I actually used to have two. Mine were a Christina (decorative pubic) and a Fourchette (perineum).
They're some of the quickest piercings to heal (you're just going through skin, and unless it's done by an idiot, it's not going through the clit - I've only heard of two instances of this occurring by incompetant, untrained piercers). This is an area that physically, you want to keep clean and free of debris and bacteria ANYWAY, and usually there's not a whole lot of aftercare for them as a result. I've only once heard of someone getting one of these piercings infected - and seeing their personal hygiene firsthand, their piercer should have never allowed the piercing to begin with.
Now, like I said - one of mine was purely decorative, and it was cute and every guy I was with was intrigued by it (ooooh, shiny things!). The other was a tiny, functional captive bead ring that would spin in and out with every penetrating thrust into me. I LOVED that piercing. IMMENSELY. And I was so happy for having experienced it. I'm FAR more sensitive down there now than I was before, even though the piercing is no longer in it.
As for people losing sensitivity - only heard of this once - one of the horrible attempts I mentioned above by someone who shouldn't have been piercing. And if someone's trying to convince you that you'll notice any type of those piercings with every step or orgasm continuously by running, going up a flight of stairs, etc... they're lying. There's not that much continuous pressure going on down there in order to cause that type of sensitivity. If there was, then the piercing would be painful, potentially swollen all the time, and the person would never be able to walk - and the piercing would eventually either tear or migrate from its original position. It just doesn't happen, no matter what they're telling you (they just want you to get it or figure someone else told them this and just because their piercing doesn't cause that, maybe something's wrong - nah, the person that perpetuated the fabricated story probably is thinking the same - that it was done wrong).
I'm not saying that a hood piercing (the appropriate term for what most people call a clit piercing) can't help with orgasm, because extra help, no matter what, can help SOME people - but definitely with a helping hand or something to conduct vibration down there.
Men's piercings are a little different, having to go through meat in many instances (ampallang, apadravya), but you have hundreds/thousands of nerve endings and you're not going to hurt them all at once, no matter what.