Why was Moses not a good leader?

Humility is one of the best and most necessary traits for a person to have; especially a leader. Moses, who had a superlative level of humility (Numbers ch.12), didn't want to accept God's mission in an unseemly, overly eager manner. First he asked God if there might be someone better suited than he. He pointed out various reasons that the mission might falter (Exodus ch.3-4), because a failure of the Exodus would amount to a desecration of God's name.