Traits must always have a drawback. If you're a big gunner or smg burster Fast shot isn't a drawback at all since they don't plan to snipe in first place.
If you're big gunner or smg burster, yes, you won't have a drawback, but... you also won't have a bonus... so what a problem?
May be my english isn't good or you misunderstood, I'll make an example:
Without traits, perk:
10mm pistol requires 4 AP to shoot torso, 5 AP to shoot hand/leg, 6 AP to shoot head/eye/groin.
With current Fast shot:
10mm pistol requires 3 AP to shoot torso, aiming shots are impossible.
It doesn't affect any weapon that can't aim.
My suggestion:
10mm pistol requires 4 AP to shoot torso, the same 4 AP to shoot hand/leg, 5 AP to shoot head/eye/groin, but you suffer -25 to critical hit table.
It doesn't affect any weapon that can't aim, prolly my 1st line in 1st post can be changed from:
-1 AP for aiming shooting, -25 to critical hit table with ranged weapons.
to
-1 AP for aiming shooting, -25 to critical hit table with ranged weapons that can do aimed shots.
So critical bursters who took Fast Shot trait won't suffer from drawback only of -20 to critical hit table incase of critical burst.