It should also be said that for most Americans, it is impossible to divorce prostrating from a religious context as we have few outward signs of reverence in our culture, but nothing as forthright as prostrations. Our whole culture is based on egalitarianism, where fundamentally each person is the same. So in the same way that iconoclasts stripped all images from churches in an attempt to remove any possibility of idolatry, in the same way there has been a sort of "iconoclasm" in terms of reverence or homage.
We don't have kings with robes, we have presidents with everyday suits that all men wear. We don't address him as Your Highness, but as Mr. President. We don't prostrate before him, we shake his hand as an equal. He isn't chosen by God and ruling with divine right, he is elected by the people and derives his power from them.
In this there is a subtle but unnoticed evil, that by removing any sense of hierarchy or divine power in the world around us, and by saying that no man is greater than "me" in office or stature, we actually place ourselves in a position where we are not willing to bow down before anyone. This begins with men, but it ends with God. Even those who do believe in a concept of God often only bow before that which serves them well or that which they have fashioned in their own vain imaginings.
Most of the self-serving entertainment flavors of Protestantism don't even offer any kind of unique physical gestures for God. Most of the time is spent sitting with a hot latte in hand during a prolonged lecture, and even during songs of worship often the songs are about the worshipper's life and orientation rather than about the being of God Himself. The most I've seen in the extreme cases of places like Joel Osteen's church is people raising their hands, but people do this for rock stars at concerts as well or for celebrities passing by on a runway, so it's not some gesture exclusive to God. I will say that plenty of the serious Protestants that I know (Pentecostal, Baptist, Emergent, etc.) do kneel and even lay before God, but they have the notion that these physical gestures are for God alone and cannot imagine them in any other context at all. I am just making the point that our culture pretty much dictates this position to them from the ground up, and it takes a lot of thought and reflection to come to another conclusion.