Here's my question: suppose I, as a kind-hearted university-based individual who respects the needs of the journals to make money but is also interested in making sure that the general public can read important scientific research, decide to upload some papers to this site. How can I be sure that it'll never be traced back to me?
Ensure that you're not the only person who owns the copy you're uploading (it could be watermarked or be a unique revision of the document).
Upload via TOR or similar.
If we can find a more efficient way to communicate research (perhaps some kind of global network of computers might do the trick?), then we should do that. We ought take no more consideration of the needs of the journals than we should for the needs of the buggy-whip makers.