Well, I gues we can see it as implicit, even though it was not explicit. Normally, we would not like to do that as it does not give the orginal event the uniqueness/dignity (not sure what the right word is). It is like saying that the Passover meal was instituted in anticipation of the mass - it just downgraded the Passover not as an event in its own right but merely to lead to the mass (even if it is truly a percursor to our mass, it was not instituted for that purpose). Seeing each event in its own right rather than something that was instituted for a future purpose gives it the true context, not an antiicpatory one. Five centuries from now, some one could be saying the same thing about an event we currently hold dear - so, my role in history ends up being just to lead up to his point in history, not very dignified of my role. Just my view, and I am not sure if I expressed it well.
For me, I find it much more interesting in seeing how events developed leading to the need to insitute each of the order of clergy. It enriches my understanding of the Church and imbued in me a sense of wonder and awe at stories of so many of the things we encounter in the Church - it is my ministry to share all these and Ifind it heartening that Catholics do find these stories of how we got to where we are today, interesting.