In fact, the presence of comments against an article has begun to act as a signal of quality. I assume that on some level the writers realise that well-argued articles backed with facts and figures mostly dissuade idiots and trolls even when comments are switched on.
While the quality of comments on the Guardian and many other news websites are generally low, if an article gets 100s of comments the top voted comments will often be decent rebuttals or positions overlooked by the main article.
A relatively decent way of reading the news is to understand the gist of an article and then head straight to the comments to see if there is a punchline. The value of comments on major media sites is to keep you open-minded and to help you spot naturally-occuring biases.