Adherence to this rule is something politicians learn at an early age -- from parents, teachers, big law firms?. When you think about it, it is not the New York Times rule that is the problem. It is the complementary rule -- "When you assert something that you may want to deny, speak it only." There is modern version of the NYTs rule that is the result of the proliferation of email. It says to ignore any question that one prefers not to answer. Think of it as taking the email Fifth. These are questions that would be answered if the interaction were in person but email mean writing and accountability. Somehow ignoring an email question provides the same kind of cover as the NYTs rule.
Why do politicians and some law professors prefer to be able to disown what they say and how far does it go? For example, do observers of the NYT rule regularly lie in depositions or in public hearings? This I cannot say but, as Mr. Gonzales' demonstrates, adherence to the NYTs rule means knowingly leaving oneself the freedom to be evasive.
There is an economic explanation for the NYTs rule. People say and write things in order to get a desired response. It gives them power. If you can get the desired reponse at a low cost so much the better. In day to day communications, the "low cost" is saying things in a form that can be denied or taken back. The New York Times rule is yet another form of greed and excessive self-interest.
There is, however, another economic consequence. Wide-spread use of the NYTs rule means that what is uttered, as opposed to what is written, is something that cannot be relied upon. This raises the overall cost of communications. Hopefully no Moneylaw school wants to raise the cost of communication in order to protect the individual interests of those who want to avoid accountability.