I don't want people to know who I am inside, and hate me/envy me for it, I'd rather they remain neutral. I've made eye contact with people before, and they've immediately told me "You're a dick" or other strange reactions. I had an ENTJ go around and tell everyone I'm creepy. I don't know if eye contact was the culprit, but I've had tons of E3's go behind my back and slaughter my reputation in the office for reasons I'm still unsure of. All I know is when I first met them, I shook their hands, looked them deep in the eyes in a friendly manner, and they were never secretly never friends with me after that.
In my mind, most people are untrustworthy until proven otherwise, and a lot of people don't like knowing this. So I hide my eyes from them so they can't read me. I'd rather be in control of how people react to me.