Before one starts claiming that the back catalog from the 90's on is all electronic...
Keep in mind the software in use. In the 90's, there were several choices of page layout software. Pagemaker, Frame Maker, Quark XPress, and TeX. Of these, the PageMaker is gone, Frame Maker isn't fully backwards compatible (due to a major rewrite), Quark likewise has had several major rewrites, and TeX was used almost exclusively in the sciences... and even into about 2000, many commercial works laid out in a page layout program had only placeholders for art, with art still being added in pasteup before color separations by filtered photographic processes were used. Getting an older edition to run on new hardware can be a pain, and getting current editions to open older edition files without needing a reedit could be problematic, before accounting for the differences in the font rendering engines between Win 3.X and Win 7/8... let alone the differences between MacOS 7.x and Mac OS X 10.X... Further, if they were running a mac shop, current Mac OS versions cannot even read the old drives. Windows can read the old windows drives, if those drives still run, but you may not be able to get that drive to run.
And that assumes that the electronic format was even kept.
And, while TSR used real page layout software, not every publisher did. Some used MS Word, and then pasted art in by hand. Others used Word Perfect, Perfect Writer, PFS:Write, AppleWorks, Claris Works, or WordStar. (Half of which, i'd guess most of you have never even heard of.) Hell, in 1996, at least one game publisher was still using Apple II GS's to lay out their stuff, while another was using a digital typecaster. (problems with file formats resulted in some really major errors on published works...)
A couple years ago, I got sent a PDF of a document from 1996. The PDF was made in 2013, from the original 1995 QuarkXPress file. The author was unable to get the fonts he'd used to install on his current hardware, and the current version of QXP relies upon the system font handling (while the 1996 version did not), and so the result is barely readable. Actually, some content isn't readable at all, except by copy and paste, and due to the font substitutions, it plays merry hell with my dyslexia... so I have (in order to use it) had to copy and paste it into a new layout. And the publisher in question was one of the early adopters of PDF publishing... but that game was one of his last dead-tree-only releases. (And one of the first open games. It really was about 4-5 years too early....) Oh, and to make matters worse, because of the particular font used in the original, it doesn't OCR worth a damn, either.
So, just because the electronic edition may have survived, even if it has, it may not be an acceptable option to publish a PDF from the original files.
