What makes you think that http requests are the only thing domains are used for? Mentioned elsewhere in this thread, Active Directory requires that the A record

What makes you think that http requests are the only thing domains are used for? Mentioned elsewhere in this thread, Active Directory requires that the A record for the bare domain be pointed to the PDC. If you're serving email from example.com, for reputation reasons you should have the bare domain's A record pointed at your primary MX. I understand that here on HN we're focused around web-based companies, but for every other corporation, there is a plethora of other services served out of a domain -- of which web/www traffic is maybe 10%, if not less. Everything from email to voip to directory services to vpns to crazy internal apps all rely on the corp's domain/domains, and you definitely should not be pointing your bare domain at your web server (which, chances are, is some contractor-built page living on GoDaddy completely outside your own infrastructure). In a typical company, you'd have some server serving example.com doing some or all of the above. It would then be running a light http server which accepts requests on 80/443 and permanent-redirects them to www.example.com. This is why www matters.