If you were, say, across a solar system from a ship that fired a torpedo at you, you'd have that much more time to maneuver (or fire phasers) to destroy it. So for those maybe it's really about effective range - you have to be pretty close to the target simply because they'd just step out of the way.

Also, I think it's a reasonable possibility phasers would lose energy over distance. Otherwise, those missed shots would travel across the galaxy and blow up someone in the Gamma quadrant or something.