Our eyes and the mouth are connected to our feelings and emotions but our eyes are the most expressive feature of our face. We are able to tell a lot about an individual just by looking directly into their eyes. We can tell things about their character, feelings, truthfulness and even health. This is why the saying that "The eyes are the window of the soul" is really the truth. From birth, we look at faces and several studies have shown that we are born with the natural instinct to focus on the face and the eyes, mouth, expressions etc. This is part of the bonding processes but it also is our first form of communication. Lovers also deeply look into one another's eyes as part of that romantic "love" connection; another bond.
Babies are born with a broad idea of what a face is, with the ability to recognize human faces babies and distinguish faces from other objects. If you show an infant a card with a series of random dots and lines on it, versus a card with a simple smiley face on it, the baby will hone in on the smiley face automatically. This is something we don't have to be taught how to do. Its neurologically hardwired into us. This is why infants and mothers/fathers spend a lot of time staring into each others' eyes, its part of the bonding process.
http://news.nationalgeographic.com/news/2005/03/0321_050321_babies.html
Now imagine, being Michael and the hundreds, thousand, even millions of people, who would be trying to look into his eyes to discern his innermost feelings, to learn as much as the could about him, to see if he felt a romantic connection to them etc.
I would wear sunglasses too, especially if I was shy. It is a way of maintaining some privacy.