There is a Folio conversation (June 26, 1975 in Los Angeles) that addresses this issue. A disciple asks Prabhupada how to explain in preaching how King Ugrasena has 4 billion personal servants when there where at that time only 2 billion people on the planet. The principle Srila Prabhupada emphasises is; 'Why discuss this point with them? Preach on another more relevant point they can accept.' Srila Prabhupada's advice may be directed specifically for the individual he was talking to in that conversation, but I think the general principle of "Don't go there if they can't accept it," is very practical advice. Just like we generally apply the principal that if someone has no inclination to philosophy, let them chant, dance and take prasadam. (I must add that this conversation is the heaviest conversation I have ever read. Prabhupada tells a disciple who asked this question to give up Krishna consciousness! Rocana dasa has given some first-hand background information on the personalities and circumstances that led to this particular conversation at: http://www.harekrsna.com/sun/editorials/talks/talks25.htm)

If you did want to answer the question specifically, I would take the discussion a step back and first establish the foundation of how one should take the Vedic literature (brahmäkñara-samudbhavam - "the Vedas are directly manifested from the Supreme Personality of Godhead," Gita 3.15, or vedänta-kåt— Krishna (Vyasadeva) is the compiler of the Vedänta Gita 15.15). Once this foundation is accepted or understood, then it is appropriate to discuss the specific details of a specific story. If this foundation is not established, there is a good chance that any discussion about the story will have no benefit for either yourself or the enquirer.

> King Pandu was the one who suggested the idea in the first place.

Yes. For the pleasure of the devotees, here is a summary: King Pandu, reflecting on the curse of the deer and his loss of the power of procreation and preparing to retire to the forest to prepare for death, ordered Queen Kunti, "Try to raise offspring in this emergency by men equal to or superior to me," in order to have sons to continue the ancestral line. He justified his order by citing the sastric recommendations regarding different classifications of sons according to how and by who they are begotten and also talked about the poor afterlife result that awaits a sonless person. Queen Kunti protested that she would never even in her imagination accept the embrace of another man and told a Puranic story of a wife who lost her husband but was later mystically impregnated by the apparently dead body of the husband. She requested King Pandu to do the same.

Continuing trying to convince Queen Kunti, King Pandu then told a story of how in former ages promiscuous behaviour by women was the accepted norm and not regarded as sinful, and that only recently through the curse of the son of a rishi was strict chastity between a husband and wife established as the present practice. He further justified his order by citing examples of when wives had been told by their husband to approach a suitable qualified rishi or brahamana in order to beget sons, and he also cited his own birth via Krishna Dvaipayana as an example of this.

At this point, Queen Kunti became convinced and told King Pandu about the mantra she had received from Durvasa Muni and asked, "Which deva should I call?" King Pandu replied, "Call Dharma (Yamaraja), there is no doubt a son begotten of Dharma will be virtuous." The Mahabharat also mentions that while King Pandu was in the forest practicing his renunciation preparing for death, he performed great austerities in order to please Indra-dev and obtain a son through him. After Indra-dev accepted the request, King Pandu then told Kunti to call Indra (using the mantra) to beget a son from him (Arjuna).

So as you can see, there were intricate, thoughtful and virtuous deliberations to determine which path of action was proper and in accordance with dharma, with each party using sastra and previous precedents to support their view. In the end the decision to beget sons through the devas was not taken lightly, and was in fact made with the full approval, participation and encouragement of King Pandu. His fame lives to this day due to the decisions he made at this time.