Practically, this is available on google books. It lacks the metadata, but google is good at searching.
Ethically, it is reprehensible to imply that Aaron Swartz was intent on piracy. (Does anyone have evidence that he was? ETA: He seems to have endorsed "guerrilla open access" in 2008; and his work on PACER is similar, though more clear-cut than this torrent. But he has used also datasets otherwise.)
Legally, it is clear-cut: digitizing a book creates a new document under copyright. Google and Gutenberg distribute these documents for free, but only for noncommercial use. ETA: this is not true about Gutenberg; it is not clear about Google.
Incidentally, the Royal Society has its own archive; this is not from JSTOR. ETA: no, this is from JSTOR.
The Royal Society's archive looks just as walled up as JSTOR's. I picked out an arbitrary volume from 1693 and tried to get the full-text PDF for a paper, but it asks for a login. I don't know if anyone can signup for free or has to buy an access package — in any case, it seems unnecessary to make people jump through hoops for papers that are (in their original form) public domain.
http://thepiratebay.org/torrent/6554331/Papers_from_Philosophical_Transactions_of_the_Royal_Society__fro
Greg Maxwell is torrenting 33Gib of public domain JSTOR documents that were behind paywalls.
What's your take on this, ethically, legally, etc?
ETA: More on this: http://gigaom.com/2011/07/21/pirate-bay-jstor/