Because then it wouldn't be FS2 with bigger guns....
I mean.. who "wouldn't" want the ability to lead your wingmen out
and have them personally targeted with a slaved weapons system... then
blast them with their own fleet...
It's just a disciplinary discharge...

I was going to say earlier that mouse turret control + multiple camera points
would equal those type of missions where you have to jump in a turret and defend the ship.
Course you'd probably need scripting or something worked in to the sub object movement,
so you could move the turret back and forth for a better range of fire...
But that's just me guessing.
There have been other uses for slaved weapons from capital ships, mostly in the SW novels
that I can think of. But none the less it's nice to hear it exists in some form.