In terms of actual content: um, The Economist. I don't think Hacker News is a particularly more valuable bellwhether of 'valuable content' for non startup/tech-related stuff than the publishers themselves (I'd say NYT, The New Yorker, and The Economist have a much better signal-to-noise for general things.)

In terms of 'deep discourse': honestly, the level of discourse in HN comments on things that are outside the traditional purview of the site is not particularly deep. I've found that if you want deep discourse about a topic X, you should seek out areas where there are many people very knowledgable about X.

If the person you're replying to is going to flag it based that vague criteria, they might as well flag much of the front page. One should start finding better articles and submitting them if they believe HN is lacking what they perceive it to be proper content.

I will vote something up is based on the quality of the article (whether it's technical news or not), if it has not already been submitted recently and if the article will lead to an informative/intellectual discussion. If it only has one of those criteria, then I'm less likely to upvote it when there's other articles that meet two or all three criteria.

plastic.com used to be a good place for such, though I fear it may be running out of users.