This phenomenon is easy to explain: the negotiators' real goals in the second round were all but attained. First of all, they wanted to prolong the negotiating process without disrupting it. Secondly, they sought to downgrade it to the "working level", because the process had enjoyed no great success at the level of deputy foreign ministers.
The key event of the Beijing round was the establishment of working groups that will conduct the main workload. These groups will comprise from seven to ten representatives from Russia, said Deputy Foreign Minister Alexander Losyukov, who headed the Russian delegation at the Beijing talks. According to him, the group should include both diplomats and nuclear experts, from the Atomic Energy Ministry for example, and technical experts.
Indeed, the deputy foreign ministers of the two Koreas, the USA, China, Russia and Japan did not gather in Beijing to engage in literary work to draft a final document, which in any case would have only been necessary to inform the public and would have reflected the positions of the key figures in the talks, North Korea and the USA, which have remained virtually the same since the August round.
The idea of the working groups appeared between the two rounds and meant that some experts could decide how exactly North Korea was to "freeze" or "dismantle" its military nuclear programmes, the existence of which has still not been proved. Meanwhile, others could work out a procedure for monitoring and checking the process and decide who was to verify the results - the IAEA, the CIA, independent experts, etc. The third group was to deal with what and in what order North Korea might get for this.
In reality, even without the official establishment of these groups, work on the "Korean problem" could not be organised otherwise, as the past few months have shown that it is the only approach that works. Month after month, everyone met everyone at the working level, discussing many minor and major issues. One can confidently say that the second round in Beijing would never have taken place if not for these meetings. At best, it would have been a carbon copy of the first one: a public row, where prestige, wording and high principles were more important than the content.
This is a classical model of multi-party diplomacy. If two opposing parties (in this case North Korea and the USA) create one unsolvable problem through their opposite positions, this issue should be divided into a few smaller and solvable problems.
As to the decision itself, the working level, as any other one, implies the same scheme that is clear to everyone. In this case, Pyongyang should give up its military nuclear ambitions, regardless of whether or not they are real or just a bluff, and in exchange receive not even economic aid, but international co-operation for the sake of reforms and opening the country to the world.
In reality, the debates concentrate on the details and the procedure, not on the principal contents of the transaction. According to North Korea's official statements, it would like "the two parties to put down their guns simultaneously", in the presence of their seconds - the four other parties to the negotiations. Washington, however, still believes that it has the right to be the second to put down its weapon, "first the full disarmament of North Korea, then we can talk economics".
No one has left the negotiations, though. Firstly, all the participants are consciously killing time until the November presidential elections in the USA, after which the word "compromise" can be uttered. Secondly, even without the elections it is impossible to sign an agreement until experts have worked out all the possible models for an agreement in a calm atmosphere and have explained to the conflicting parties how they can put down their guns.
Therefore, this "prolonged" option is so far suitable for everyone.