It seems apparent that we can't actually do what was done back then originally, since the first Passover was the actual exiting event. And we likely can't do what was subsequently done, because it likely morphed over the years of tradition. The intent would have been the commemoration, and it appears there is nothing like food or the lack of food to reinforce a ...well... such an impactful collective memory. (Word suggestions welcome here.)
I can't speak for God (and who can?) but what comes to my mind is that I suspect the intent God had was for the people to return annually to the roots of that event and see what it was that He did in bringing them out. Annually, this would have been followed in roughly 7 weeks to the celebration of the giving of the 10 Commandments and the Law, the reciting of the Blessings and Cursings, which is really a reinstatement of what makes life work and what makes calamity come more quickly. Both of those events would have reinforced the reality that God is, that God gave us good rules that make life work for us, and that we are so prone to forget them and get off the track. It's just the nature of how God is and how we are. Such a foundational premise would warrant annual reminders.
Since there didn't seem to be much concern expressed by Jesus over the way the tradition of Passover had morphed from the Exodus to the Last Supper, nor the fact that apparently Jesus was quite comfortable holding this commemoration on the day before He was to be that Passover Lamb once and for all in the heavenly view of things, and since Jesus told us to remember His death until He comes, it looks to me that there is some degree of lee-way here in how we commemorate, although I would suppose we are always wise to stay close to the original definition as well as the original intention until or unless the point is apparent that in observing the definition we have defied the intention.
The Church at large has taken this tradition away from the Jewish roots into a papal kind of liturgy that has been handed down to the various branches of Christendom. Therefore there will be a lot of solid resistance among Christians in general to anything other than that the current liturgy is the right interpretation of how God intended this cultural shift to happen. I would question that because it seems to me that Jesus had ample opportunity to more clearly lay out behavior changes that would be coming so that we are not deceived. I perceive that it is entirely possible that the cultural shifts were actually a series of compromises and could have been the gist of what Jesus meant when He said the Kingdom of God was like a small green plant that grew into a giant tree and had birds nesting in it. I'm not sure, but like you, I have thoughts when I read what Jesus taught and the message of Jesus would accurately show what God intended, fleshed out right in front of us. I have wondered when I look at what should be a solid consistency in what God is doing with man from the beginning through Jesus' own example, whether we have misunderstood what God meant when He established the next covenant. If my mom or dad said, "Hey, kid (interpreted from Attend, my beloved offspring because I genuinely want the best for you), the deal is..." then I would understand that my parent wasn't shifting intent but was shifting focus to help me "get it" by offering me a different phrasing in order to win my voluntary buy-in. Since God doesn't change, well, I don't see Him changing intent. He has loved us from the beginning and is still calling us to turn toward Him and fully buy-in to His love.
So my question to the original poster and to the subsequent posters would be this: If there were no outcry of heresy to whatever you chose to do, how do YOU see the commemoration of this dynamic event happening in your family or circle of friends so that you meet the intent of the original? What do you see in scriptures that supports your view? What confusions do you encounter when you hold on to traditions in light of what you read in the scriptures? If it came down to just you and the God who loves you dearly, what do you see Him saying to you in this example of the Passover/Exodus/Last Supper and what do you think would honor Him in your commemoration of it annually? It might be worth the examination.
God remains the Authority, not me, but this is what came to mind, phrased in the frailty of words.