Though a cool thing to have, the problem I see is that the fact that there would be a lot of chat logs in just a few hours on some servers, and it would be hard to find anything specific we might be trying to find, even if we do manage to keep it from recording plug-in chat messages. However, some coding and sorting might easily fix the problem.
I just hope that if this does become a thing, staff members don't nitpick and get as much people in trouble as possible for unnecessary reasons.