This forum is pretty PG rated compared to a lot of online forums. I can't think of any occupation where you really need to be disassociated from this forum in general. Now if you want to be a dick and hide behind a screen name that seems like a weak reason to allow anonymity. If you're in law enforcement, or a professional of some kind, why would you care if people know you waterski?
When I'm not skiing, I do a lot of competitive shooting. As you can imagine, that community has a large overrepresentation of law enforcement, and quite a few of my friends from that community are not your run of the mill local police, but of the more secretive variety. They tend not to want their names showing up on facebook/forums/etc, and go through pains to make sure that their scores only show up with pseudonames or initials. But even those guys are the minority.
But it doesn't bother me one way or another. My name is in my signature, and I use the same forum handle everywhere, and an internet WHOIS will give you my name anyway. Others don't want the same level of publicity, and bury their info a little deeper. I don't think it detracts from the forum.