Egos seem to be everywhere. I'm starting to think it's manners as much as humility and openness that helps keep them in check.
As for criticism, tell people to be open. Tell people to be brutal, if need be. Sometimes the best thing you can do to change, is let yourself get hurt a little bit. Do you guys ever do writing exercises? Not only do they help you guys become better writers, they also help you become better critics and more receptive to criticism.