They had the same capabilities in SE4 Ed. They didn't have the fire rate of a ship for missles carring 'direct fire' warheads. Anti ship missles would 'Ram' and you could even put drones (like a Multi-Warhead) on the missle. Due to the three turn re-arm cycle. They weren't too effective.
Because of their superior speed on the tactical map I always found drones without any weapons or warheads were best used to blockade the worm holes/warp points. Enemy ships would just chase them around until one or the other ran out of resources.
Seems like exploitation of the AI's limited capabilities. Not much of a strategy and a waste of resources jars. If you had played with 'finite resources' [on] you wouldn't be wasting resources on such items.