Israel was built on priesthood. Not only is she destined to be a priesthood to the world during the Millennium, but she herself required a priesthood in the days of Moses.
Today, I compare Exodus 19 and 20 with Ephesians chapter 3. Anyone who does not see differing administrations and dispensations after today's MZTV is simply not paying attention. (You may continue to disparage "dispensationalism" at your own risk.)
Priesthood belongs to an era of immaturity, before a full revelation of God had come. Now we see
God in the face of Jesus Christ, Who calls us His brothers. Today, we have direct access to God Himself, through Christ. Any suggestion of priesthood, now, to the body of Christ, is a slap in the face of the Christ with Whom we enjoy face-to-face fellowship.