It sometimes becomes a common sense thing to do.  

Scenario: 

A topic generates a side issue which is generating responses that are based on the side issue instead of the PageTopic. Rather than deleting the comments generated, the discussion is moved to a page with the PageTopic in agreement with the side issue. This is a GoodThing to do, since rather than having a fractured, out of focus discussion on several topics on a page, the material and the discussion is moved to its own page, where no confusion of topic is generated. 

The effect of doing this generates additional pages and focused material. The usual result is that one provocative page with many implications ends up generating several good pages linked together by their relationship to the original page and to each other. 

It also removes the tendency of people involved in the side issue complaining that the page title is incorrect and should be something else.  I find when such comments are made, it is definitely time to make the move.  Content on Wiki is much more helpful and enjoyable when it is properly identified and classified by the page title.
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A side effect is that clicking on the page title of this page will generate page names on which the DiscussionMoved Link has been placed. The addition of this link on the old and new page could prove helpful in this respect.