Near as I can tell the weapons are supposed to go as follows:
Fixed have dps but are fixed and can therefore only be used when you are more maneuverable than your opponent
Gimbals have middling dps but are gimballed and can be used against opponents that you have a small disparity in maneuverability with
Turreted have low dps, but aim all around and can be used against opponents that you have a large disparity in maneuverability with
Except the DPS of gimballed and turreted weapons approaches zero when the enemy has chaff activated, and they can equip as many chaff dispensers as utility slots and synthesize chaff. This makes gimbals less useful but still viable as you are at least somewhat able to keep guns on target and get maybe some of your dps on. With turrets, it takes a weapon with an already niche use and makes it worthless. Combine this with the plasma experimental and you have a meta that would already be pushed towards fixed because of higher potential DPS pushed entirely to the end of the spectrum where non-fixed weapons would be better described as non-viable.
If you ever want to see how broken chaff is, equip a sidewinder with a pair of chaff dispensers and your choice of loadout and go kill a battlecruiser in it. Sure it may take forever because of the low dps but the fact that a fighter with an FSD can singlehandedly take out an entire battlecruiser without even losing shields is just obscene.
I don't have a solution, asides from removing chaff entirely, and would therefore like to brainstorm.