Something about not violating copyrights is absolutely appropriate for a code of ethics. You're not violating a copyright if you're quoting something with the purporse of discussing it and attributing it's source. That's fair use. But just taking other people's work and posting it, either as your own, or with out anything added then yeah, that's a violation, and it's not really ethical.
Rail against copyright law all you want... I mean there are definately problems with the system, but thems the rules.