Once upon a time, I drank this koolaid, but no more. Many things in life are ephemeral, including information. To suggest that a webmaster's responsibility is to hoard data for eternity is both scatological and counterproductive. As the Web matures, it is threatened far more by the growing mountain of obsolete information that must be ignored in order to find anything timely and relevant. I would much rather see these pages deleted if they aren't going to be updated, even if it means broken URIs, which will eventually fade away.
I think people have been confused for a long time about what the Cool URIs essay means by "change".
This is a particular resource:
http://example.com/latest/
It has representations that change over time, because the conceptual resource "the latest thing at example.com" itself changes over time. This is perfectly fine: the resource that the URI refers to stays the same, but that resource's state is mutable, and the changes in this state are reflected by changes in the resource's representation (what you get by retrieving it.)
This is another resource:
http://example.com/2012/01/02/news/
This representation at this resource probably shouldn't change very much; not nearly as much as the one at /latest/. It's still allowed to be mutable, though! If there's a typo, or a retraction, you're allowed to reach back through time and fix that resource, to make it "the way it should have been" at that date.
A webmaster's responsibility is to make sure his URLs continue to refer to the same things they originally referred to. Conceptually, if you only want to store "the latest news", then you should only have a /latest/, and not a /2012/01/02/news/. Creating the latter is creating a promise that it will stick around, continuing to refer to "the news at 2012-01-02"--a permalink, in the real sense.
I think another important aspect of this is that the (relatively unchanging) resource at /2012/01/02/news/ shouldn't be moved to /archive/2012/01/02/news/ without at least a redirect.
The point being that if the resource still exists, the old URI would preferably still point to it. If you, as the arbiter of the resource, decide to remove it, of course the URI will break.
There as many kinds of websites are there are types of paper publications. Nobody cares about old TV magazines, but there are plenty of books that are older than me and still relevant. The online version of SICP, for example, has incoming links from many universities that I hope will never break.
Yeah.. I think the desire to keep everything around forever, untouched, is an inability to organize and distill, or maybe an unwillingness to at least try and find out it's possible. The web as an endless roll of toilet paper rather than a library is a sad development.
