A laser makes it more likely that you will be accurate when point-shooting, which is the way most people tend to shoot when freaked out.
When you do your dry-firing training, make sure that consciously activating the laser is part of your drill. The way you initially grab the gun (when freaked out) is likely how you'll hold it when shooting, and it IS possible not to activate the laser.
True, a laser is not a substitute for iron sights. But the reverse is also true. Unless you're a gun-fighter by trade, my guess is that you'll be point-shooting in a defense situation regardless of whether your laser is activated, and regardless of whether your gun even has a laser.
~Ichiro