I also think that would make sense. Paywalling is a legitimate business strategy amd I don't fault these companies for wanting to get paid for content creation. However, HN is an aggregator so many people can't view an article like this. If a paywall article is posted, it would be nice to have a link to a plain text version or alternate link. I think this would be a good compromise.
Not really, many online publishers allow direct access to shared links as an enticement to potential subscribers, it's like turning your reader base into your sales force.
I never knew this, cool! I think HN mods should negotiate some sort of deal so the links can be non-paywalled if you are coming through news.ycombinator.com.