There are a lot of pluses and minuses to turrets sharing shields of the parent ship, and each advantage and disadvantage can go either way.
With the current system small ships can get in between the fire arcs of turrets and disable the turrets. This promotes fleet mechanics, namely smaller ships supporting larger ones and individual ships having a more specific roll.
Turrets with their own shields would weaken the turrets as space that could otherwise be used for firepower is replaced with defense. This also requires that the main ship has at a minimum one weapon system.
If shields were shared then that would enable more powerful turrets for the same size. It would also enable ships who's primary means of attack is turrets, this would also put greater demand on pilot skill and turret placement. Small ships would be less useful, while specialized medium and large ships would be more useful (Example, a ship with anti-shield sege weapons for disabling enemy ship shields), this would also require more fleet communication in order to exploit the 10 second gap when shields are down.
Game-play wise, I think shared shields is more in dept as to my knowledge there are zero science fiction universes with energy shields that turrets do not share main ship shields. It would also make shield information universal, if the main ship's shields are low then the turrets shields are low.
While small ships would be less useful in fleet combat, I like the idea of having shared shields. Currently when in combat I am most concerned with my turrets receiving damage, because it is difficult to calculate at what strength their shields are at.
If you are to take into consideration the new weapon systems, then one can argue that the small ships are now only useful for early game. In fact there are no rapid fire single computer weapons tuned for fighters.