My criticism is not necessarily constructive. ;) But it's not too hard to imagine something along the lines of arXiv combined with a rating/commenting system

My criticism is not necessarily constructive. ;) But it's not too hard to imagine something along the lines of arXiv combined with a rating/commenting system not unlike HN itself, combined with a Facebook-ish algorithm for surfacing articles relevant to each reader. The devil is in the details, of course, but it shouldn't be hard to do better than the expensive, artificially constrained, and arbitrary system we're saddled with now. The real trick will be convincing entrenched academics to switch -- I'm still not convinced this is actually possible.