This is a misunderstanding of an unchanging God. Since God is eternal, the concept of him changing is only our changing interaction of him. That "changing interaction" includes what we are now versus what we were in Old Testament times.

If our situations of today (I'll pick on widely available pornography, just for fun) were available in Jesus' time, God's reaction would have been the same.

HE hasn't changed, we have. Thus, we need to "rewrite" our interaction with him as we try to understand the changing world under His law.