The answer is - he doesn’t like to kill us. In the old testament Moses wanted to see God.
Moses said, “Now show me your glory.” - Ex. 33:18
But,” he{God} said, “you cannot see my face, for no-one may see me and live.” Then the LORD said, “There is a place near me where you may stand on a rock. When my glory passes by, I will put you in a cleft in the rock and cover you with my hand until I have passed by. Then I will remove my hand and you will see my back; but my face must not be seen.” - Ex. 33:20-23.
God doesn’t like to kill Moses and mankind by showing himself. We can’t even see the glory of the sun closely. How come can we see God, who created the sun? Isn’t he trillions upon trillions times brighter and powerful than the Sun? Aren’t his power and glory so powerful that could consume humans?
The LORD your God is a consuming fire - De. 4:24.
In revelation God’s glory is incorporated.
At once I was in the Spirit, and there before me was a throne in heaven with someone sitting on it. And the one who sat there had the appearance of jasper and carnelian. A rainbow, resembling an emerald, encircled the throne - Re. 4:2-3.
From the throne came flashes of lightning, rumblings and peals of thunder - Re. 4:5.
This is the glory of God. Man can’t see him face to face.
It was written that Moses talked to God face to face. The phrase "face to face" in the Hebrew mindset means "personally," "directly," or "intimately." Moses had this kind of unmediated relationship with God. But he, like all other mortals, never saw an actual "face" of God.
Being "face to face" with God simply refers to being in God's direct presence in an intimate way.
In Genesis 32:30 Jacob said, "I saw God face to face, and yet my life was spared."
Jacob thought it was God, but it was an angel of God.
Manoah enquired of the angel of the LORD, “What is your name, so that we may honor you when your word comes true?” He replied, “Why do you ask my name? It is beyond understanding - Ju. 13:17- 18.
The angel of God said the same answer to Jacob.
Jacob said, “Please tell me your name.” But he{angel} replied, “Why do you ask my name?” - Ge. 32:29.
Therefore, it’s a key text to refute that Jacob saw God ‘face to face.’
I hope now you understand why God doesn’t show himself to mankind.
