The horse buggy might also have not disappeared, but that doesn't mean that better transportation hasn't overtaken them. My point being that we should try to leverage new formats and structures for conveying information. Also, PDF's are pretty bad for anything other than print. Imagine linking a DVM to analyze the text of papers, but this one (http://bayes.cs.ucla.edu/BOOK-2K/ch1-3.pdf) ends up being in your pile. Try copying and pasting the text in there, which a script would try and scrape from the file.