The Jews realized the importance of remembering what the Lord has done for us. Likewise we observe the Lord's Supper. There's a reason why we do this, it's a very important reason.
When do not remind ourselves of the great and mighty works of the Lord. If we are not continually mindful then how will our children know what God has done for us?
The Jews in Persia had learned from their former mistakes. They set up a Holiday as a memorial of God's works. Just as we erect memorials to war heroes and past presidents, even more importantly we should have memorials to our children of what the Lord has done for our lives. Our children should know our testimonies, and be taught to share their testimony with their children!