A public display of an address gives the spammer free range to spam away.
Or worse, gives virus attackers an address to use. They don't even look at the information. They usually just run scripts to gather e-mail address information from public web sites.By default, I've set the default option to not display addresses. You can choose to display the address in your profile if you want, however, keep in mind, it is fair game to spammers and Microsoft virus attackers.