When you register a domain name, you have to give them all sorts of contact information about yourself, or risk losing the domain outright. It's become a rich repository of information for all sorts of people, including spammers. Should you be allowed to register domains privately?
Privacy wasn't a big consideration when the current addressing system started in the 1980s. Back then, government and university researchers who dominated the Internet knew one another and didn't mind sharing personal details to resolve technical problems.
Today, the Whois database is used for much more. Law-enforcement officials and Internet service providers use it to fight fraud and hacking. Lawyers depend on it to chase trademark and copyright violators. Journalists rely on it to reach Web site owners. And spammers mine it to send junk mailings for Web site hosting and other services.