I don't mean to be a stick-in-the-mud, but isn't there a danger to ascribing spiritual explanations to every single mundane action?
If memory serves, I think Fr Alexander Schmemann takes a similar track in "For the Life of the World." (Of course he never argued that we should remove such things as unnecessary or anything like that, which would not be Orthodox. We don't seek to determine what is the minimum necessary for a "valid" Liturgy.)
I personally think that mundane actions can take on a greater meaning. These meanings are wonderful and add great richness—but should not be treated as dogma or be the cause of arguments. We don't need to deny the practical origins either. Liturgy develops, it's a fact.
As another interesting note, I've heard the Great Entrance was originally the priest walking to a table where the people put bread for the offering, and choosing a loaf to use for the Eucharist. The procession was kept, even when that practice of bringing bread was no longer done. Now it seems to represent Christ's entry into Jerusalem.