There hasn't been a need for copyright declarations (in order to assert copyright) in U.S. law since 1989, either.

A quick précis: "All rights reserved." is totally pointless chaff. A copyright declaration still has a modicum of use, but most of the pre-1989 requirements for it have gone.

* http://jdebp.eu./FGA/law-copyright-all-rights-reserved.html

On the other hand, it's a rather diminute investment, the benefit being that if you ever have to sue someone for infringement, you can unequivocally state that the infringer had been put on notice that the content was copyrighted, thereby helping your case. A meek help, true, but the benefits seem to far outweigh the "investment" of adding a copyright notice to a document.