I was thinking of mentioning the same thing. For me I think it is that the internal paragraphs are about the same size as the breaks between comments. Also I like the way that the Original Hacker News uses grey for the user name and dark for the comment, that provides more differentiation between comments. Also, using bold for user names attracts my attention to the least important part.

To give a positive comment, long comments are easier to read on this version.