Thanks for this. I am shocked to learn that re-recordings of previously copyrighted work are not deemed derivative works and actually receive their own separate copyright even after the original has expired.
What exactly are you shocked by? Are you saying that you can perceive the work a composer does as creating something of value, but you can't see how the work done by an arranger or a performer adds value to that original composition work? In the pop world, where the majority of artists don't write their own songs, there is an incredible amount of additional creative input between the songwriters handing over their guide track and the producers/performers releasing the finished product. If the moral principle behind copyright is that ownership of any original creative work remains in the hands of its creators, then it makes sense that those arrangers and performers should retain the rights to their own contributions, separate from the work of composers and lyricists.