User blog comment:Merlaa/Pendragons - The Diamond of the Day./@comment-5674726-20121229001036/@comment-5674726-20121229154755

I'd say that they didn't want the trouble of having a birth storyline, and all the requirements for the infants cast as Baby Pendragon, but they also didn't want to bother having a succession crisis/Arthur under pressure to set Guinevere aside and find a new wife, in the hope that he will have children by her, storyline.

Instead, they took advantage of a precedent established for a troll, of all people, to have Guinevere as the successor.