I'm not an expert of the development of the silent Canon of the Mass, but it is the traditional and ancient practice (if you go to any traditional Latin Mass, you will not audibly hear the Canon). I can only relate my own personal experience of it.
[Forgive me if this is clumsily expressed--it's late, and it's not easy to describe] For me, the silence at the consecration emphasizes interiority---instead of listening to the priest out loud, we are imbibing the miracles expressed in the Canon to the depths of our hearts. We listen to the Holy Spirit in silent awe at that cosmic moment when Heaven and Earth and temporality and eternity meet.
Somehow it is deeper and more meditative when I say the Canon in my heart rather than listen to a priest say it out loud. It's that sense of interiority again.
I am reminded of something Cardinal Ratzinger (now Benedict XVI) wrote in his brilliant book, The Spirit of the Liturgy (a must-read, BTW):
In 1978, to the annoyance of many liturgists, I said tha tin no sense does the whole Canon always HAVE to be said out loud. After much consideration, I should like to repeat and underline the point here in the hope that, twenty years later, this thesis will be better understood. Meanwhile, in their efforts to reform the Missal, the German liturgists have explicitly stated that, of all things, the Eucharistic Prayer, the high point of the Mass, is in crisis. Since the reform of the liturgy, an attempt has been made to meet the crisis by incessantly inventing new Eucharistic Prayers, and in the process we have sunk farther and farther into banality. Multiplying words is no help---that is all too evident. The liturgists have suggested all kinds of remedies, which certainly contain elements that are worthy of consideration. However, as far as I can see, they balk, now as in the past, at the possibility that silence too, silence especially, might constitute communion before God. It is no accident that in Jerusalem, from a very early time, parts of the Canon were prayed in silence and that in the West the silent Canon---overlaid in part with meditative singing---became the norm. To dismiss all this as the result of misunderstandings is just too easy. It really is not true that reciting the whole Eucharistic Prayer out loud and without interruptions is a prerequisite for the participation of everyone in this central act of the Mass. My suggestion in 1978 was as follows. First, liturgical education ought to aim at making the faithful familiar with the essential meaning and fundamental orientation of the Canon. Secondly, the first words of the various prayers should be said out loud as a kind of cue for the congregation, so that each individual in his silent prayer can take up the intonation and bring the personal into the communal and the communal into the personal. Anyone who has experienced a church united in the silent praying of the Canon will know what a really FILLED silence is. It is at once a loud and penetrating cry to God and a Spirit-filled act of prayer. Here everyone does pray the Canon together, albeit in a bond with the special task of the priestly ministry. Here everyone is united, laid hold of by Christ, and led by the Holy Spirit into that common prayer to the Father which is the true sacrifice--the love that reconciles and unites God and the world. (pp. 215-216)
Finally, Scamandrius, I think the silent Canon (a tradition that is very ancient in the West, being fully established by the 7th century) is something that functions in a similar way to the iconostasis in the Eastern Divine Liturgy. This idea of "veiling" the holy of holies, of course, goes back to the ancient Israelites.
I don't have a problem with the audible Canon, really---I see different advantages to both practices.