I think its really stupid and a totally turn off. Why would men want to pierce their penis. How are they able to have sexual intercourse and go to the bathroom without it getting it infected or hurting the girl.
Why do women get their nipples or any area between their legs pierced? Some people just like the feeling or how it looks. Why do people get tattoos on their face or wear pants that look like the pants are just about around their ankles? I don't think you can explain it. I think it's like any other thing people do. They do it because for some reason they like it.
As for me, I wouldn't do it if you paid me. I also don't like women with pierced nipples or any are between their legs either.