Traditional forum style sorting just sorts for controversiality. Posts that generate heated discussion will continue to push their way to the top. This is okay but it means that non controversial stories will not make it to the top, which is honestly one of the largest benefits of news aggregator sites.
How about, here and on reddit, being able to mark threads you're interested in, and having a page where you can see those sorted by last reply. On HN, make that page refresh every 15 or 60 minutes or whatever. Heck, once every 24 hours would be enough... sometimes I just want to talk about the things that interest me, with the people that are interested in them. I would love to be able to think on something for a few days, or to familiarize myself with a subject before mouthing off.
As they are now, reddit and HN are require you to be there when something is "current", and that's ultimately not that much better than TV. Yeah, sometimes you can get something out of it, but it's nowhere near as useful or deep. Even worse, there is a tendency to get semi- or unrelated stuff one out when something slightly similar is discussed, instead of putting things exactly where they "belong", where they add to a useful corpus. [which is exactly what I'm doing right now, and am doing too often.. but I honestly would prefer the alternative which doesn't exist yet]
Just think about it, we have practically infinite storage, there's certainly plenty of expertise in reach of HN -- yet discussions get constantly restrained because our attention is limited. But it's limited because all we get are these flat lists, X items per page, next to no means to curate or organize anything. Imagine how much worse it would be without people who sometimes link to old but very relevant and insightful stories or individual comments. I'm very grateful to them, but to take them for granted, to rely on them for "structure" is totally stone age to me. Give us tools, give us transparency, let us figure out things even if they might be hard - stop trying to hand hold people you might underestimate! We don't need you as much as you need us.
I completely agree that a large problem with news aggregator sites is that you must be there right when the news hits. Eventually in the HN algo, time always dominates score and the discussion is killed no matter how interesting it was.
To be honest, I think that a change in behavior needs to come from the website, top down, rather than allowing the community to opt in to an alternate scheme that will never hit the popularity threshold necessary to work. Like a sibling mentioned, Reddit has "newest", but because it's not on by default, no one bothers to use it.
I don't think that it's our attention spans that cause our browsing behaviors on aggregator sites- I think it's purely derived from the Ui/Ux of the site, and that if the site kept interesting conversations up longer, people would participate and have more than the surface-level reflexive remarks we see here. This is not just a hypothesis - we can see the alternate behavior born out on forum sites. I think it's a huge shame that HN has opted for this model (especially when it wants to be "the better news aggregator"). Think how many great conversations never happened here because the algorithm prematurely killed the thread - due to lack of upvotes or something else.
Another failing of the UI/UX on some social news sites is not being able to CC other posts. If there are notifications, alerting only the parent of new activity only does so much.
While sdrothrock is correct that these sites don't have much incentive to produce quality discussion, I do agree with you that there's value in seeing what gets votes as opposed to what gathers replies (not that they are necessarily mutually exclusive and not each plagued with their own problems). I wonder if it's worth trying a system that marries the two elements. Take a conventional BBS, for example. They often have a reputation system that in the best case encourage quality contributions and avoid posts only consisting of "good post, I agree." However, they can't be used to indicate from the index what discussions are worth treading. You can try highlighting the top voted comments[1] beneath or side-by-side their respective links to the OP. Then you can infer what kind of discussion is taking place. Is it a bunch of metajokes or did someone just unload a lot of expert knowledge?
For news aggregators to facilitate enduring discussion is trickier as the nature of news is to remain current. Maybe if a link would otherwise decay but discussion is ongoing, the news entry on the index could take a backseat to its most 'active' threads. Indented new lines underneath the post that link to those threads, "The conversation is still going. Click to expand" or something like that.
[1] Perhaps highlighting only a number of posts proportional to the total number of comments or only the posts above a minimum score that is proportional to the total number of comments (just so you don't get highlighted for being one of the first responders). It's also probably important to not be able to vote on the post from a preview, so people have to click into the thread and hopefully read it and possibly contribute.
> As they are now, reddit and HN are require you to be there when something is "current", and that's ultimately not that much better than TV.
One thing I don't think people have addressed is that that's the goal for them; it's not necessarily to be "useful" to the end user. If they can make users feel like they have to be on reddit 24/7 to stay "current" and not miss anything, then they will. Facebook does the same thing.
And with reddit gold you can even have it hilight all new replies regardless of sort order. This can be really useful for viewing older discussions and see what's been added.