Since the velocity physics of missiles in the game seem to be properly modeled (i.e. final missile velocity = missile "static" velocity + ship velocity), the range of fire should be adjusted accordingly.
Currently you can have a really fast ship and gain no range advantage over the enemy (which should be the case-- and is the case in real fighter jets). This is due to the missile flight time being the determining factor. If the final velocity of the missile is greater (with respect to the target) then it takes less time to travel the same distance if the ship was static. However, compared to the static case, you should be allowed to fire sooner if the ship has any speed because the flight time will still be the same. Basically, the relative velocity between the missile and the target ship needs to be constantly calculated and the firing range should be updated accordingly.
I also think that this would give missiles a necessary buff. I hope this all made sense.