Why did God judge Moses so harshly? What was really going on in Exodus 4:24-26? What was the big deal with Moses striking the rock instead of speaking to it?

Links:

Why was God going to kill Moses in Exodus 4:24-26? - https://www.gotquestions.org/kill-Moses.html

Why was Moses not allowed to enter the Promised Land? - https://www.gotquestions.org/Moses-promised-land.html