The truth is, 4Chan is full of some of the best people in the world.
It has changed in the last few years and the change has been even more dramatic in the last 6 months or so. The long September started last year and now people are coming to 4Chan expecting nothing more than to cry havoc and let slip the dogs of war. They have no interest in the history of 4Chan or in creating new content.
They come because it's trendy.
Just like Usenet, /., Digg, Reddit, and someday HN, the people who matter will leave and find a new home.