Amazon stops publishing public domain content

Amazon has updated its Content Guidelines, the high-light is:

Public Domain and Other Non-Exclusive Content Some types of content, such as public domain content, may be free to use by anyone, or may be licensed for use by more than one party. We will not accept content that is freely available on the web unless you are the copyright owner of that content. For example, if you received your book content from a source that allows you and others to re-distribute it, and the content is freely available on the web, we will not accept it for sale on the Kindle store. We do accept public domain content, however we may choose to not sell a public domain book if its content is undifferentiated or barely differentiated from one or more other books. 

This is a good signal, Amazon is working hard to offer us good quality content, but not the junk eBooks with the stuff copied from Wikipedia.