"God is in the West, North, and South---too."
Yes He is.  Facing East, whether actual east on the compass or "Liturgical East" symbolized facing Jerusalem where the sacrifice took place (and takes place).
"It is the people who also offer their prayers and worship to God---not just the priest with his back to the people."
That's why I said "we offer the sacrifice of the Son".  Recall the priest says "May the Lord accept the sacrifice at my hands and yours...".
The priest is not turning his back to us, he is facing Liturgical Eat with the whole congregation and offering the sacrifice of the mass.  If you think about it, the priest facing us has to make the mass about himself - Is he interesting? Does he seem bored or troubled? Is his hair nice? Does he seem tired? But the mass is not about him or his quirks.  Facing east with the people, his personality diminishes in importance as his individuality is totally subsumed into the awesome moment of sacrifice.   
Just some thoughts,
Pax 1LB