* we want to look spiritual
* we think the Holy Spirit likes closed eyes more than opened eyes
* we don’t want to look at the faces of people who seem apathetic, concerned, confused, or angry about what we’re doing
* we’re battling fear of man and the easiest thing to do is just pretend that no one else is around
* we don’t want to see who walks out of the room
* we’re discouraged by the dwindling number of people showing up on Sundays
* we’re imagining that this is our own personal encounter with God
* we don’t remember the words to the next verse
* we can’t think of anything better to do
Not to mention that worship leaders who shut their eyes sometimes look more like they’re in pain than in God’s presence.
I especially like the last one! Also, don't forget about his book.