This has been an issue discussed for a long time. See https://news.ycombinator.com/item?id=10178989, as linked to from https://news.ycombinator.com/newsfaq.html, for some context as to why things are the way they are.

I personally agree with the decision. The discussion generated is still valuable even when I can't read the whole article. A lot of the paywalled sites are generating content that's more valuable than the average blog, which is why they're able to survive behind a paywall to begin with.