The fact that the game expects some common sense in part of the players and GMs as to what they try to do and how they limit the uses of certain items, etc.. SHOULD go WITHOUT SAYING.. that is, not need to be printed. It should be expected that a group of people sitting around a table to play the game will employ some common sense when playing said game. I mean, the term has the word common right in it. Now, admittedly, I have found that it is increasingly less common but none the less, we shouldn't need to have the rule book spell out to use that we should use it.
I would HOPE that most mature, informed, and knowledgeable gamers would not find such a passage useful but instead down right insulting to our intelligence and ability to operate as human beings. The day I look in a book, read a passage stating: Please, in your arbitration and interpretation of these rules apply common sense. And think to myself, Hell! That was useful, I am glad they put that in there I almost forgot about that... is the day I stop gaming.
Ok.. this is a touch over dramatic but I think it helps get the point across.