Talks, even among actual belligerents, are almost always undertaken. But first at third-hand (Spain in WWII carrying messages between Allies and Axis), low-level bureaucrats (e.g. suggesting trade negotiations), high-level bureaucrats (Consuls and Ambassadors bearing messages from the governments they represent) etc. to set, yes, pre-conditions prior to actual meetings. Heck, there were pre-conditions concerning Winston Churchills visiting with Franklin Roosevelt - the two "Naval Gentlemen" were not exactly representing antagonists.

So the question is what is meant by "without pre-conditions." If BHO meant not setting terms of possible problem resolution (while perhaps agreeing on an agenda of things to be discussed), fine. And if he'd say so, fine. But that is not waht is coming from him or his handlers/staff/supporters, even though I think it is what he meant, and that is worrying for an over-reaction to what should be a minor point.