Another thing to consider is what constitutes a karma point. I don't have any statistics to validate, but it seems that posting new submissions rewards more karma points than responding to submissions. Maybe the Admins/Mods could run some stats and see if this is true or not. While I do not personally care about karma points (I'm here because I actually enjoy the community), basing the ability to vote (as in, influence the ranking of what is presented) on a single metric that does not differentiate between submissions and comments likely results in a skewed representation of the community.

To put it simply, if you want lots of karma points, don't bother responding to submissions (presumably in an attempt to help someone with a problem, or contribute to the conversation). Instead just find some "hot" controversial articles on some other tech related news sites and submit them instead. If this is true, then it should not be surprising that there is more "white noise" here at HackerNews, as this approach facilitates submitting stories instead of contributing to conversations.

My recommendation (if anyone cares), break karma points up into two separate values, one related to submitting articles/stories (which is valuable), and another related to submitting comments (which is also valuable). Then I would remove any reference of points from the system (make them hidden from users) as to remove any desire to "game the system" for points. This would result in a system where points do not influence how people contribute to the community.

You need 500 pts to vote on HN

I only have 63 points and I can vote (but rarely do). Actually I can only upvote. I think 500 is for downvote rights.

You're right my bad. 500pts to downvote

I wonder if that asymmetry is part of the problem. There's a large population of users who can push junk to the top of the page, and a much smaller population with the ability to downvote it.

You can't downvote submissions; you can only flag them.

Stack Exchange does this.