Yes there is a good reason, many of them in fact: archival purposes. Academic purposes. Research purposes. When most publications make a mistake or find out something pertinent after the fact, they add a footnote to the bottom clarifying it. They don't simply cut a new revision of the same issue with the story changed.
The PDF file format offers a fantastic mechanism for adding callout annotations. Use that feature to note issue #1. Address Bitcoinica's fall in issue #2.
+1