There's a lot of discussion here about comments and votes, but only one or two remarks in this thread note the clearest differentiator I see between "old guard" and newbie users: the meaning of the up/down arrows.
Old guard would prefer to vote on a "Contributes/Detracts" axis, while new users vote on an "Agree/Disagree" or "Like/Dislike" axis.
Arguments about this erupt in threads, with newer users generally saying, "It's a democracy, this site is what the majority want it to be, and if most of us want it like this, your loss." But such an approach devolves into pop pablum.
I believe most other ideas here would be unnecessary if the meaning of the up/down arrows could be resolved either socially or algorithmically.
The "correct" solution would be to offer a quadrant, with contributes/detracts on one axis, and agree/disagree on the other. But that would require a rewrite.
Instead of a rewrite, I'd experiment with temporarily changing the arrows to say something explicitly supporting well reasoned comments:
17 points by uptown 1 hour ago [ contributes | detracts ] link | parent | flag
Some would undoubtedly still interpret these as a rightness axis like "agree/disagree", so perhaps an even more familiar pair of terms:
17 points by uptown 1 hour ago [ content | spam ] link | parent | flag
However, the term "content" might lead to voting up every valid content remark, so the positive word should be something with more of a value judgment, while still being a word that can apply to points of view with which one disagrees:
17 points by uptown 1 hour ago | interesting* | spam | link | parent | flag
The idea with the vocabulary choice is that a neutral comment would not be clicked on, and "interesting" is directly in the HN charter.
I think this type of vocabulary is more in line with the desire to see well reasoned or contributory discussion flourish.
* Mouse over the word "interesting" could tooltip: "This comment made me think."
// This account is ~400 days old, but a prior anonymous account is ~800 days old, giving some perspective on the trend over time.