Interesting. Why do you choose 12kT escort carrier/fighters rather than, say, 2x6kT escort frigates with turrets? I would have thought the fighters are much more expensive in terms of fuel /losses/micro for no real advantage in PD terms?
Versatility, mostly. Speed is key to many things in Aurora, I have been recently surprised by a FAC-heavy spoiler race with overwhelming numbers and if I had slow-ish escort frigates I would have lost the entire fleet. Instead, I gave them some fighters to chase while running for the jump point, and it worked. I lost my fighters, but my fleet will fight another day.
Fighters are cheap to build and replace, can be built anywhere by throwing a bunch of factories on a planet, and their speed is a valuable asset.
I'm not saying I don't have escort frigates with turrets as dedicated PD, just that all my major fleets have a couple carriers as well.