I don't even advocate the feature as a form of "problem prevention" - moreso it is simply something I see as an integral part of any such system. Both as a player and [i]especially[/i] as a GM, I'd like it to be there (I see it as my duty as a GM to player do explain why I made the decision I did, designated box for it or no). It is furthermore not a "heavy" addition to code in. 

As a sidenote, the no-posting list will also need to have an undo function.