if the recording is no longer available no-one has been deprived of a profit if it is copied. The continued availability of the music in mp3 format could, however, stimulate enough demand for it to be re-released.

Yes and yes. The big question for me is, what message does the availability of deleted music for free download send to the owners of the rights? I think the main message is

Remember this? We do!

And I think it's a powerful way to send that message - possibly even more powerful than starting a thread on Mudcat...