I don't think that would make any real difference. Links break because people switch to new software that has different URIs for the content and they don't see

I don't think that would make any real difference. Links break because people switch to new software that has different URIs for the content and they don't see the problem, or due to software that has stupid mechanisms for generating URIs, that's it. URIs changing due to a concious decision to change the URI are the rare exception, it's mostly just a side effect that noone cares about. Also, in your specific example, it would still be possible to replace the old content with a document explaining the change and linking to the new URI, or possibly even an HTTP redirect. Plus, a semantically meaningless name might still not prevent the problem, as there just as well could be legal consequences if you have communicated before that this URI provides "current prices" via some other means than the URI itself.