Why doesn God reveal Himself to people today, like He did during Biblical times?
He does, exactly the same way. Noah, Moses, Abraham, etc. were all believers when God revealed Himself to them. I don’t believe there is even one instance in the Bible of God revealing Himself to a non-believer. There are many people today who claim to have had God reveal things to them, or who have even claimed to have met Jesus. They are often dismissed as hallucinations or delusions, but the same was true of people’s responses to Noah, Moses, Abraham, etc.