The Levites were dedicated to be servants of God.
Celebration of the Passover was important to God. Why? Because the ceremony was to be a reminder to the people where they came from, of their deliverance. This would hopefully help prevent them from wanting to go back to Egypt.
Take note of what the Passover feast was made up of. The lamb represented Jesus. The lambs bones were not to be broken-Jesus bones were not broken. They were to eat bitter greens. This was to remind them of the bitterness of slavery. It is a reminder to us of the bitterness of sin. Jesus had to partake of the bitterness of sin and death. Bread without yeast. Yeast is symbolic of sin. Jesus had no sin.
Even with the pillar of fire and the cloud the people would still rebel against God. That is why when the religious leaders would command Jesus to perform a miracle, He would not do it. He knew that even miracles will not change a person with a wicked, hard heart.