There are safety regulations that those stores must comply with in order to operate. They include fire alarms, emergency exits, fire sprinkler systems, and a long etc.
Hopefully there will never be an IKEA fire during a busy time, and we'll never know if those regulations magically made it easier to exit the extremely-confusing (especially to a child that is seperated from parents during confusion) layout.
Are you a trained firefighter? I was. Children will hide in the darnest places during a fire instead of escaping. IKEA is full of places for children to hide. Almost makes me wish I could have played hide-and-seek there as a child.