Why has God never revealed himself to us?

The Bible is primarily a collection of books on how God revealed himself to us, little by little, in accordance with the spiritual maturity of humankind over the ages. The pinnacle of revelation was with Jesus Christ, who as part of the Trinity, revealed the Father and Spirit to us to the degree that we know all that we need / can know. The rest of the New Testament describes what happened after and clarifies theological revelations.

If you mean personal revelation, some people claim to have had them, and others not at all. But God still has revealed himself through his word.

If you wonder why God just doesn’t make himself blatantly obvious to us in a physical way, it is because the collective sin of the world has put a “screen” between God and us – we cannot fully stand is his presence, and our perceptions are dim and dull. We just don’t notice it since it is all that we have ever known.