But if that (Gen 3:7) is the meaning of “knowledge of good and evil,” then why did God forbid it? Why does God not want them to have wisdom?

There seem to be two reasons. First, as a loving father, he knew and greatly feared that they were ill-prepared to face the vicissitudes of such a world. Surely he did not want them to suffer, and he knew they would. Second, he knew that any such efforts to make themselves more “godlike” would end in abject failure, because they were not, in fact, godlike; their attempts at greatness would only bring heightened grief upon all, which is what happens to whomever has like ambitions. The most eloquent commentary on such ambitions is the famous passage in which the Lord says of the “Day Star,” also translated “Lucifer,” “For thou hast said in thine heart, I will ascend into heaven, I will exalt my throne above the stars of God” (Isa. 14:13). Yet God rebukes him roundly: “Yet thou shalt be brought down to hell, to the sides of the pit.” (Isa. 14:15) Lest you think that God was anti-intellectual and forbidding an attempt to get wisdom, you must bear in mind that this was not theoretical knowledge, but rather direct experience of the dubious benefits and especially the deep, tragic costs they would bear without the blessings of his holy presence and guardianship.