Thank you for the interpretation question, “Why are the Ten Commandments in Exodus 34 never discussed?”
As I read Exodus 34 and your question, it appears that the words, “never discussed” needs to be clarify.
When we use the term, discuss, it infers questioning, debating, and perhaps a compromise. It’s talking about the topic/subject to see if both parties can come to some agreement. That form of discussion and agreement may be viewed as conditional covenant whereby both parties agree to certain stipulations.
In Exodus, God is making a unconditional covenant with his stipulations or commands if the Israelites want to live under the rule of God. The bases of this unconditional covenant are that God has delivered the Israelites from Egypt and promises to bring them into the Promised Land. He offers to them that they will be his people and he will bless them if they agree to follow his commands. The Israelites agree to the unconditional covenant made by God with their part to obey God’s command.
The Israelites didn’t negotiate with God exceptions to his commands. It was his offer to them. They or individuals were free to walk away from that covenant or to accept and follow it. The choice was theirs.
Perhaps, I may be reading too much into question, but in Exodus 34 God expands on the Ten Commandments. if the question is about expanding or expounding the Ten Commandments, God provides greater detail on the Ten Commandments. It is very specific.
Exodus 34 says this, “10 Then the LORD said: “I am making a covenant with you. Before all your people I will do wonders never before done in any nation in all the world. The people you live among will see how awesome is the work that I, the LORD, will do for you. 11 Obey what I command you today. I will drive out before you the Amorites, Canaanites, Hittites, Perizzites, Hivites and Jebusites. 12 Be careful not to make a treaty with those who live in the land where you are going, or they will be a snare among you. 13 Break down their altars, smash their sacred stones and cut down their Asherah poles.[a] 14 Do not worship any other god, for the Lord, whose name is Jealous, is a jealous God.
15 “Be careful not to make a treaty with those who live in the land; for when they prostitute themselves to their gods and sacrifice to them, they will invite you and you will eat their sacrifices. 16 And when you choose some of their daughters as wives for your sons and those daughters prostitute themselves to their gods, they will lead your sons to do the same. 17 “Do not make any idols.
18 “Celebrate the Festival of Unleavened Bread. For seven days eat bread made without yeast, as I commanded you. Do this at the appointed time in the month of Aviv, for in that month you came out of Egypt.
19 “The first offspring of every womb belongs to me, including all the firstborn males of your livestock, whether from herd or flock. 20 Redeem the firstborn donkey with a lamb, but if you do not redeem it, break its neck. Redeem all your firstborn sons. “No one is to appear before me empty-handed.
21 “Six days you shall labor, but on the seventh day you shall rest; even during the plowing season and harvest you must rest.
i highlighted some of the verses that shows that God elaborates on the reasons for the Ten Commandments.
Summary: God offers a covenant with the Israelites of what he requires for them to become his people. It was not subject to negotiation. The Israelites can accept or reject the offer of God. It was their choice.
-Kingston