That was a very interesting part of study I did early in my theology years, namely that divine revelation to Moses and others included theophanies (visions of G-d) but the Jews still believed that if they saw G-d that they would die--even after G-d proved otherwise by demonstration.
You read this all through the Tanakh, and like Vivane says it is a contradiction. What it demonstrates, regardless if the stories are meant to be historical or just legends, is that the Jews are repeatedly described as disbelieving G-d.
G-d appears to Moses as fire burning in a bush, and Moses readily looks at it until G-d tells him he is seeing G-d. Only then does Moses shield his face.
This happens again at the Great Theophany, at the foot of Mt. Sinai, where G-d appears as a great fire on the mountain and even speaks, but the people won't have it, believing they will die if G-d keeps showing himself and talking. But later Moses and elders from the tribes have a "meal/meeting" with G-d face-to-face on the mountain.
The theme actually runs throughout the Tanakh and is related to the reason why Jews are called the "children of Israel" and not the "children of Abraham." Israel (Jacob) wrestled with an angel, or theophany of G-d and wouldn't stop once the roughhousing, so to speak, came to end. G-d had to wound Jacob to end the situation.
The underlying lesson is that the G-d "concept" is something Jews have always struggled with. It demands a level of trust and faith that Jews have not ever been comfortable with. We don't believe in submitting to G-d. G-d put us here, in the mud, so to speak, and expects us to live our lives alone? No way, Jews say, you put us here and we're bringing you down with us, down into the same mud! It's a fight to define G-d as G-d, to re-define G-d as history moves, and to allow G-d at the same time to be self-defining...and then arguing with G-d about it all. That's why its totally acceptable to be a Jew who is atheist or agnostic. We are thus children of Israel, those who refuse to submit to G-d.
So you will read G-d saying it is okay to see G-d, and Jews telling him that they will die if they see him. It's a running theme (or maybe even a running joke) in the Scriptures.