Why evacuate on the same side/wing as an engine fire?
Did many of the other passengers who were unable to see the left engine try to slow the evacuation by grabbing personal items from the overhead or under the seats?
Many passengers have no idea how many exits are behind them-they often tend to swarm to the main cabin door up front.
Maybe we will learn whether the Captain was able to talk directly with the Rescue/Fire Commander. There is often a frequency which the pilots can use for this.