Egress windows provide a safe and easy way of exiting a house in case there is an emergency such as a fire. In addition to acting as emergency exits, egress windows also make it possible for natural light to reach the basement.
Basement air is usually stagnant. There is very rarely fresh air or air circulation. These larger windows allow you to open up and let the clean airflow. That makes the air in your basement healthier, and therefore, the air in your home healthier.