The giving of the Torah is not a clear and direct process.  First, God chooses to teach the Torah to the Benei Yisrael only indirectly, speaking to Moshe and having the people overhear.  Then, the people choose to distance themselves even further.  Even this mediated intimacy proves to be too much for the people, and they ask Moshe to go between them, so that the information is relayed from God to Moshe and only then from Moshe to the people.