Respectfully:
Why not? From a perusal of the Pentateuch there's some extremely dated laws. A New Covenant that affirms the essence of the Old Covenant but bringing new laws for the civilisation envisaged in Isaiah makes most sense.
From a similar perusal of Tanach, you will notice a relatively large number of verses commenting on the eternalness of the Laws of G-d. We do not believe the Laws of G-d are dated or ever will be.
There Laws are the essence of the Covenant and it stands eternal.
I'm not sure how you think changing the Laws will make more sense vis a vis the civilization prophesied by Isaiah.
The Hebrews obviously despite clear instruction forgot their God including worshiping other Gods. One obvious way of looking at theses verses is that in the future His people will obey HIs commands for the love of God, and not out of fear. They will love to obey God and the New Covenant will inspire that love. They will no longer forget their God.
The passage makes no comment about love or fear of G-d, nor is such an interpretation implicit. Its based on the Christian concept that the "old laws" were based on fear and the "new laws" are based on love. But we do not see it that way. I bring you Psalm 119 and Song of Songs as the greatest evidence of that.
On the one hand you seem to want to keep the law as it is, on the other you want to dispense with the Sacred Texts altogether as God somehow or other talks directly to His people.
The "Sacred Texts" only have value in that they convey the information G-d wants to give over. Its not the mundane words themselves that have meaning, but the information that they teach.
At the very least you seem to be binding God's hands preventing His revealing further laws.
We are taught that after Moses no prophet may convey new Laws. This is consistent with the eternal nature of the Laws.
The Christians often make the error of interpreting the Gospels literally. I wonder if you are doing the same?
There is a difference between a verse like Proverbs 9:1 that speaks of Wisdom hewing out 7 pillars and a passage like this. We know that Wisdom is not a physical thing that can hew stone. So there is a compelling reason to interpret this verse as a metaphor.
But here, the passage is clear and my interpretation is consistent with the rest of Tanach. What compelling reason is there to assume that the literal interpretation is not the correct one?