I'm not much of a 2chan fan but they're certainly not unique in that respect. What about USENET? It's been around since the Internet was born (maybe even before, depending on what you mean by "born") and there has never been the means to moderate discussion. That's why it's such a wasteland. And nobody seems to care.
If I had to guess, I'd say someone at 2chan said something that pissed off someone in "government" -- in which case, I'd say they're probably worth keeping around. But it's not something I'd ever be interested in following.
What I really wouldn't want to see is for a precedent to be set where governments of any sort can shut down conversations they don't care for.
They care about all the posts for drugs and prostitution that remain up long after being informed about them. A lot like what happene with craig's list and them getting serious about it. Also the recent rise in people looking for jobs like hitmen and such.