It can be useful for moderators to be able to see the flags history. And what I mean by flag history is two things:
Flagging history of single users
Flagging history of single chatrooms
Flagging history for users can be useful for moderators to see how many flags the user raised, or what they flagged, and whether most of their flags are nonsense and declined or had actions taken based on those chatflags.
Flagging history for single chatrooms can be useful for moderators who for instance come to a room where there has been flagging activity but has been dealt with by other mods, so all that needs to be done is look at the history instead of asking around about what happened. With this feature mods could see old and recent (dealt with) flags of a room.