See previous discussions of this issue, which are easily revealed by Google if the fitting keywords are used in the search:<p><a href="http://news.ycombinator.com/item?id=494421" rel="nofollow">http://news.ycombinator.com/item?id=494421</a><p><a href="http://news.ycombinator.com/item?id=711613" rel="nofollow">http://news.ycombinator.com/item?id=711613</a><p><a href="http://stackoverflow.com/questions/4285617/how-do-i-install-arc-to-get-a-hacker-news-clone-website" rel="nofollow">http://stackoverflow.com/questions/4285617/how-do-i-install-...</a>
Unrelated, but there are good open source clones like <a href="https://github.com/antirez/lamernews" rel="nofollow">https://github.com/antirez/lamernews</a>
Ask OP: Why SHOULD it be open source?<p>1. Asking "Why isn't it this" without a "this is why it should be this" is such an easy argument it must always be ignored<p>2. Hacker News is a Y Combinator entity. If it were to be open source, it would be open source to YC people only I can only assume.