Given that the same articles come up over and over again, and attract upvotes and comments, it seems clear that the userbase gets value out of reposts.
Perhaps the HN software should turn the knob the other way, and automatically repost old links which got a lot of attention previous times.
I wonder how many of Hacker News' current users were around in pre-2012. This sort of post could be "new to them"-- they may never have thought to search for the topic, and the repost could bring new perspectives.