I came here to write almost the same feedback suggestion, even if it is just a '+1' or 'Like' style to highlight the better comments, although I'm a fan of the YouTube style with up and down giving the post a 'score'
While we do come to read the articles, many of us like to engage over the topic or content, and we do so in the comment section (mostly). When a story has 100 comments, you naturally want the best ones to float to the top, and the trolls to fall to the bottom. User voting is the best and easiest way to achieve this.
If you look at Slashdot as an example, they have a voting system, and a meta voting system so that consistently poor voter's votes are excluded.