Lets assume that God did change his mind based on Moses's intercession. Lets see what supposedly changed God's mind. From Exodus 32:
12Wherefore should the Egyptians speak, and say, For mischief did he bring them out, to slay them in the mountains, and to consume them from the face of the earth? Turn from thy fierce wrath, and repent of this evil against thy people.13Remember Abraham, Isaac, and Israel, thy servants, to whom thou swarest by thine own self, and saidst unto them, I will multiply your seed as the stars of heaven, and all this land that I have spoken of will I give unto your seed, and they shall inherit it for ever.
This is Moses's argument in total. In simple terms, his first appeal is "what will the neighbors think" ? Do you really think God cares what the Egyptians think ?
The second argument is almost as lame. It boils down to reminding God of his promise. Does anyone think God needs to be reminded ? Or does God get so angry he cannot he forgets his promises ?
Next, how effective was Moses's intercession ? Look at 35
And the LORD plagued the people, because they made the calf, which Aaron made
Well that went well. God didn't consume them, he sent them a plague.
If Moses did not make a persuasive argument in Exodus 32 and again in Numbers 14, Why did God Almighty say this:
Jeremiah 15
1 Then said the LORD unto me, Though Moses and Samuel stood before me, yet my mind could not be toward this people: cast them out of my sight, and let them go forth.