Rate of fire can mean the difference between taking out an enemy before they get a shot off.... or needing to start the level over. A Weapon Supercharge will give you 30 seconds (?) of ultra-rapid damage dealing for any of your weapons. Even Dark Troopers will melt against the onslaught of supercharged blasters.
Just be careful that you don't hold that trigger down constantly, or you'll find yourself out of ammo before the supercharge even ends.