This is a question for believers...all other just pass by it will bore you..lol?

because God wanted to be glorified by the miracle of water coming from a rock when spoken to. Moses was mad at the Jews and struck the rock twice and said he now ye rebels must we fetch water from this rock. Moses and Aaron did not get to go into the promised land because of Moses hitting the rock and not bring the glory to God. thanks for the question.

I don't know, and I don't think anybody else does, either.  The Lord wanted different things done for reasons of his own, and we are supposed to obey the Lord's current commandments, not the ones of 3,500 years ago or 2,000 years ago or 20 minutes ago.  Live by every word that proceeds out of the mouth of God.  Seek the church that has a living prophet and apostles, which are the foundation of the church of Jesus Christ.

The rod/staff was the symbol of Moses' divine power and authority. Once that had been established before the people, his word alone could be enough. 

I think God was testing Moses to see if he would obey and speak to the rock. He failed the test.  

The difference is that the 1st time was Less than two months after the Israelites left Egypt, a serious problem arose even before they arrived at Mount Sinai. The people started to complain about a lack of water.

  Jehovah responded by giving Moses clear instructions. He was to take his rod and strike the rock, and then water would come gushing out.

2nd time was some 40 years later, toward the end of the journey through the wilderness?   The Israelites once again complained about the lack of water. Num. 20:1-5

Once again he turned his eyes to Jehovah for direction. But this time Jehovah did not tell him to strike the rock. Moses was told to take his rod, gather the people before the crag, and then speak to the crag. Num. 20:6-8

 Moses did not, however, speak to the rock, or crag. Rather, he vented his frustration by shouting out to those gathered there: “Hear, now, you rebels! Must we bring out water for you from this crag?” 

He then struck the crag not just once but twice.

Because you have to kind and polite to rocks to get them to give you water. 

Even if you hit a rock with a sledge hammer and bust it to pieces, it will laugh at you but not give you any water.

But if you sweet talk a rock, compliment its good looks and speak of its generosity, you can milk it dry!

I am free to answer any questions I please. And I please to tell you that is the way the author chose to write the fairy tale.