Exodus 12-13:16

The passover meal originates with God (rooted in divine revelation and authority), therefore it is not a tradition that can be altered by man. God is the God of new beginnings, and He wants His people to remember this in their new calendar.

The passover meal is to be communal not just for an individual. That being said, there were boundaries/requirements and distinctive beliefs associated with the meal. 

It is a highly symbolic meal (details correspond to other things that God has planned: Christ's sacrifice). Bitter herbs are included to remind the Israelites of the hardship they had faced in Egypt. They were to be dressed and ready to go.

2 themes: judgment and death for those not protected by the blood of the lamb; deliverance and salvation for those who are protected. This teaches that what made salvation possible was a substitute: every household was going to experience death (of the first born or a lamb).

The meal not only looks back at what the Lord has done, but what He has promised to do. While it is good to know, and perhaps observe, the Passover meal and all it represents, it is not mandated in the Christian calendar. Instead, we celebrate Jesus' death and ressurection with the Lord's supper.