Hey there!
For the benefit of other readers:
Exodus 22:18 "You shall not permit a sorceress to live." This cross-references with Leviticus 19:31 "You must not turn to mediums or spiritists; do not seek them out, or you will be defiled by them. I am the LORD your God."
Leviticus 20:17 "A man or a woman who is a medium or a necromancer shall surely be put to death. They shall be stoned with stones; their blood shall be upon them"
Practising the occult, something God hates, goes against God's exclusive right to reveal the truth and guide his people (Israel at that time). If people went against this law then they were essentially rebelling against God and cutting off their relationship with Him, plus it can lead to idolatry, another thing God abhors. This was the Law at the time and to go against it was to go against God's covenantal rule, and to damage the community. It's no good if people are following other 'voices' and not following the teaching and laws given, it results in chaos and harm.
What changed in the various churches that this verse was no longer applied ? I mean that in terms of preaching.
Well, the person of Jesus Christ came! These laws were specific to the nation of ancient Israel. Jesus has fulfilled the Law (Matthew 5:17) and he bore the penalties of all sin on the Cross (Colossions 2:14.) We are now under the New Covenant which means the Church wields spiritual, not civil, discipline. So no putting people to death because they dabbled with a Ouija board. However the Church very strongly warns against occult practices.
Galations 5:19-20 warns against it "Now the works of the flesh are evident: sexual immorality, impurity, sensuality, idolatry, sorcery, enmity, strife, jealousy, fits of anger, rivalries, dissensions, divisions, envy, drunkenness, orgies, and things like these. I warn you, as I warned you before, that those who do such things will not inherit the kingdom of God."
Revelation 21:8 is pretty clear "But as for the cowardly, the faithless, the detestable, as for murderers, the sexually immoral, sorcerers, idolaters, and all liars, their portion will be in the lake that burns with fire and sulfur, which is the second death."
Today we prefer people confess this sin, repent (turn) from it and are forgiven. Why couldn't they be forgiven then? Because they were under a different covenant and Law.