BSD-ish licenses are "permissive", in that you can release modifications/derivatives of the work (in binary or source) that restrict how those modified versions are distributed.

e.g. I write a BSD-licensed song, and someone remixes that song and says that I cannot copy the remixed version.

How does that take away any of your rights, though? The BSD licensed song still exists.

Thats one of the most common argument against the concept of copyright. They say: How does a copy take away any of the authors rights? The original work is still there regardless how many copies are made by p2p file sharing.

Which has been stated before in this comment thread. If we abolish copyright, GPL is not needed. If we keep copyright (and thus accept the concept of derivative copies effecting the author), then GPL request freedom.

Please pick one. We should not cherry pick the arguments depending if one is talking about copyright or GPL. The same argument can't be false and true at the same time in the same mind.

The original exists, but the modified versions that are now prevalent are works that do not grant me my rights. I have contributed to the arsenal of my adversaries; my works have become part of the works that deny me rights that I consider important, the right to share and remix.

Whereas when copyright is abolished, if I have the song I can copy the song. They cannot put terms on it that would withhold my freedom to do so. I don't really need the GPL anymore; I don't demand anyone's source code, just my freedoms with the knowledge and information that is available to me.