Essentially, when communicating his will to people who revere him, he wants things to be orderly and clear; when dealing with wicked people, God will bring confusion upon the wicked party on purpose to impede their evil act.
I'm also reminded of:
Exodus 23:27 (NIV)
27 “I will send my terror ahead of you and throw into confusion every nation you encounter. I will make all your enemies turn their backs and run.
Samuel 14:20 (NIV)
20 Then Saul and all his men assembled and went to the battle. They found the Philistines in total confusion, striking each other with their swords.
Confusion is for God's enemies/people acting like his enemies, in disobedience to his ways, (and by extensions Israel's enemies); clarity, on the otherhand, is for God's friends. The closer a friend, the more clear he'll be (thus why he spoke in parables to the public, yet clearly explained the parables to his disciples; why he spoke in dreams to other prophets, but face-to-face with Moses).
Exodus 33:11 (NIV)
The Lord would speak to Moses face to face, as one speaks to a friend. Then Moses would return to the camp, but his young aide Joshua son of Nun did not leave the tent.
Numbers 12:6-8 (NIV)
6 he said, “Listen to my words:
“When there is a prophet among you,
I, the Lord, reveal myself to them in visions,
I speak to them in dreams.
7 But this is not true of my servant Moses;
he is faithful in all my house.
8 With him I speak face to face,
clearly and not in riddles;
he sees the form of the Lord.
Why then were you not afraid
to speak against my servant Moses?”
Matthew 13:10-11 (NIV)
10 The disciples came to him and asked, “Why do you speak to the people in parables?”
11 He replied, “Because the knowledge of the secrets of the kingdom of heaven has been given to you, but not to them.
Enemies in confusion; Friends in clarity.
3nodding