Honestly I don't think there is anything wrong with turrets, I think its the fact that engine upgrade is so stupidly ridiculously good on big ships. If engine upgrade was small ship only, i dont think there would be nearly as much of an issue.
I hear this a lot and it always bugs me. Engine Upgrade on a large ship isn't dramatically better than on a small ship.

If you're boosting away, the end of your ship is in the exact same place that a small ship would be. If you look at the front of the ship, it is only 1 small ship base further forward - which is about 1/3 of a single range band. So, it's handy for boosting into range 1 or 2, but not a big deal when you're running away.