It is simple. I honestly like it a lot compared to what passes for forums nowadays. I'm still working on what I hope will be a decent open source clone in Laravel for the masses (though i don't doubt someone else also is and probably better.)

A lot about hacker news could be improved, I think, like adding a JSON api by default and being able to control the depth level of comments. More importantly though, I think the simple format facilitates discussion a lot better than the noisy, avatar-riddled nightmares like phpbb, etc.