"'I think, myself, [Gaia] is in the same position as the traditional God. Being good, she wants to share existence with others, and so creates them. But to make them puppets, automatons, would be senseless. They have to have consciousness and free will. Therefore, they are able to sin, and do, all too often.'"
-Poul Anderson, Genesis (New York, 2001), p. 193.
(Why not, in at least some created/emulated worlds, "Therefore, they are able to do good, and do, very often"?)
Gaia is not omnipotent. The difference between very great power and infinite power is qualitative. These issues have been discussed here, here and here. In haste, folks, but I hope that these links are worth reading.