It is not just for our enjoyment. It is because we are called to learn from God's holy days. An so we will be helpful servants for the people in the Millennium.
God instituted a system which will teach people during the millenial and post millenial age to recognize the consequences of sin, and to resist sin. This leads them to conversion and faith in Jesus Christ's sacrifice. Eventually all believing persons are blessed in Abrahamic faith, and all enemies of God are destroyed. Our Father comes to Earth to live with His Children!
Peter leaves Christians with warnings about troubles that will come in this age.
Comparison is made with the world to come, during the millenium period.