Pretty sure that's been the plan for a while now though. There is a thread somewhere around here about just that thing. It's on my todo list to add the option for smart turrets, which will have target selection independant of the ship they are attached to (like capship turrets do).
The change would do two primary things: 1) allow a turret to fire at an attacker of your ship, or your target (if your target is friendly, or just in protection mode for AI), and 2) allow a turret target preference (ie, allow you to focus on a bomber, allow turret to focus on bombs). And #2 would also go with capital ship targetting, where it would prefer to fire at enemy turrets targetting you, then turrets in general, then subsystems. A turret would never fire at a target simply to fire at it (like they do now), but actually target subsystems of anything they shoot at and prioritize targets based on danger level (like capship turrets can/do).
This would make the turret into more of a true defensive weapon rather than just an extra gun. You could effectively be following, and firing upon, a hostile ship while your turret(s) fire at any hostile ships following or firing upon you. But the main point is that the turret will always be looking for something to shoot at and should never just be sitting there doing nothing if there is a hostile, any hostile, in range.
I looked into this at the time it was originally mentioned, but haven't really thought about it since. When I actually get ready to start working on the code for this (unless someone else gets to it first), then I'll likely bring it back to the forums to be sure that everyone is in agreement about how it should work. There will likely be more on the wishlist for this particular feature for mods by then anyway.
