Many people believe that Jesus was God in human form.
He supposedly came down here to show us how to live.
Following this logic I would have to assume in order to live as a man he would have had to face the same temptations as any other man in order to get his followers to believe it was possible to emulate him.
If on the other hand we just saw him as god and he was never tempted by anything nor had the same desires as man which may require being controlled then his lessons would be less effective. Without God truly experiencing life as a man it would be impossible for man to believe he could live his life as God wants.
God came down as man to lead by example.
In many ways the story of Jesus is a version of the current hit show on CBS called "Under Cover Boss".
He came to live among us to experience our joys, pains, sorrow, and temptations. People tend to respect teachers and mentors who have walked in their shoes.