Well the forum is completely open for anyone to view. I think there are probably still some people who just like to live a private life without having their lives easily viewed by all and sundry on the internet. Nothing mischeavious at all, some people are just more private. Simple.
There are also many levels of personal safety to consider. These days it could be relatively easy to find out where someone lives, given their real name etc. If person X says that they will be doing a particular race on a given day, then they have effectively broadcast to the world that their home will be empty and all their Walshes* easily stolen.
Marco has outlined some of the more serious reasons why a reasonable person may not want to broadcast their identity.
*minus the pair being used for the race.
