Does adding "All rights reserved" have no legal usefulness?
Currently, copyright is assumed to the authors unless explicitly declared otherwise, and no rights are granted unless explicitly declared.  Thus, de facto your work is "all rights reserved" even if you don't explicitly state it.  

Please do make sure you explicitly state copyright information, however, including name and durable contact information!  The assumption of strong copyright protection even without explicit notification is actually a big problem for effective sharing of information both inside academia and outside, because people often reserve more rights than they intend to, and lack of good copyright information makes it difficult to correct this.

A number of organizations are building systems intending to simplify this type of interaction.  One of the most notable is Creative Commons, whose licenses your see all over Wikipedia.  Other similar ventures and consortia exist for software, electronic hardware, mechanical blueprints, DNA, etc., each of which has its own unique set of IP problems, often intensified by the interaction of copyright with patents and less well-known IP systems such as EU sui generis database rights.