Point taken. Perhaps you are right.DrPaul wrote: This is an interesting question. Perhaps the answer can be found by reading Ch.1 of AATE where we learn that, for ages prior to his arrival in the Land, Lord Foul had been exploring the Earth and experimenting with different powers in order to try to find some tool that would serve his ultimate purposes. Even after entering the Land he tried different strategies at different times (which is, after all, why we have three Chronicles as well as the back story of the battles between Foul and the Old Lords).
On this basis we could conjecture that the RoD was another of Foul's experiments. He may, for example, have hoped that the puissance of the Ritual would awaken the Worm of the World's End.
But Foul never totally mastered the Land. The first time he was close to total domination, he destroyed his own armies and reduced himself for 10 centuries.
IMO he should have finished defeating the forces of "good", tortured Kevin to death at his leisure in the Creche, and then maybe taken a few hundred hears trying to find some way to break the Arch besides Desecration. If he came up empty, he could probably find some other tool or lackey to enact the Ritual with him.