I'm going to jump right on in here and say it; the 3 degrees of jitter isn't actually all that terrible.
The problem is, it's terrible in comparison to other weapons. Allow me to explain as best as I can, using my favorite thing ever, math!
So, if we assume you like to engage your targets at the maximum allotted range on your standard beam type weapon of choice, the magical Burst Laser, that puts you at a 3 km range. Based on testing and visuals and that even gumball and turret beams have a maximum range of 3 km (without the Focused upgrade), we can do some rather simple triangle math, given the angle (3 degrees), the length of two sides of the triangle (3 kilometers), to get the maximum width of our Cone of Fire ( abbreviated CoF from here on in, for simplicity's sake), which comes out to 157 meters. This actually isn't bad - remember, this is the full diameter of the circle that you will hit, not the radius, meaning that if a ship is approximately 75 metes wide by 100 meters long and mostly square, you'd actually hit them rather decently, though you'd miss a lot of shots as most ships are - per the rules of "The Slot" - shorter than they are tall and wide, and most have some form of tapering. Still, this is enough to, assuming you keep good angles, hit a Corvette at this range with at least 30% of your shots.
Now this CoF goes "down" (technically it gets smaller but it's not actually getting smaller, but for the sake of brevity I won't explain in detail here) to 104 meters at 2 kilometers from your target, shrinking again at 1 kilometer (the usual distance I engage at in Elite) to about 52 meters. Remember, these numbers are the diameter of the circle. If you can, fit a 52 meter across circle on the top or bottom of a ship, you can reliably hit it at this range, making most of the boxy ships rather easy to hit. You'll need optimal angles, of course, but a good pilot can still make use of this. It gets to a rather respectable 26 meter CoF at 500 meters - ramming ranges and some of the closer quarters fighting I've seen in space - which still leaves smaller ships to be a significant problem.
Now, I will admit; this isn't terrible, but when there are other experimental effects that perform more reliably, and whole other weapon classes that fight better in these ranges, and it also leaves you essentially wide open to being eaten by smaller fighters without some other weapons to pick up the slack, it is a very niche weapon. That niche being smaller, maneuverable ships fighting Corvettes and other heavy tanking ships.
Now, my request is to move the jitter angle down from 3 degrees (as measured by arc; 1.5 degrees from center) to 2 degrees. This still makes it challenging to hit smaller ships, but gives you a much better chance, bringing your 3 kilometer CoF from 157 to 104 meters, your 2 kilometer CoF to roughly 70 meters, 1 kilometer to 35 meters, and 500 meter CoF drops to a much more reasonable 18 meter circle. This would still keep the weapon in the niche - fighting larger ships while having them in your limited hard-points to bust shields and hull more quickly on an agile fighter - but also not ruin a fighter's day when he gets rolled up on by another fighter.
Another potential would be 1.5 degrees arc ( 0.75 degrees from center ); which would bring things from a 78 meter 3 km CoF, a 52 meter 2 km CoF, a 26 meter 1 km CoF, and a 13 meter 0.5 km CoF. Still niche, but much more usable, allowing you to even start to try to hit fighters with non-guided munitions.
An example of the current CoF (and how I figured out that it was 3 degrees Arc not 3 degrees from center for the cone of fire calculations )
[Yes it's sloppy; I turned black to alpha channel in order to superimpose the lasers over top of each-other, which is what's causing that "really bad CG" effect on everything. There's also a laser on the far side of the ship firing at the same time ]
TL;DR - It's not bad, but it could be better, and because it's as bad as it is, other things do a much better job of it, making it a useless upgrade on an a weapon already regarded as bad. Changing the CoF would help fix this and might actually cause these to be used more then never.
The problem is, it's terrible in comparison to other weapons. Allow me to explain as best as I can, using my favorite thing ever, math!
So, if we assume you like to engage your targets at the maximum allotted range on your standard beam type weapon of choice, the magical Burst Laser, that puts you at a 3 km range. Based on testing and visuals and that even gumball and turret beams have a maximum range of 3 km (without the Focused upgrade), we can do some rather simple triangle math, given the angle (3 degrees), the length of two sides of the triangle (3 kilometers), to get the maximum width of our Cone of Fire ( abbreviated CoF from here on in, for simplicity's sake), which comes out to 157 meters. This actually isn't bad - remember, this is the full diameter of the circle that you will hit, not the radius, meaning that if a ship is approximately 75 metes wide by 100 meters long and mostly square, you'd actually hit them rather decently, though you'd miss a lot of shots as most ships are - per the rules of "The Slot" - shorter than they are tall and wide, and most have some form of tapering. Still, this is enough to, assuming you keep good angles, hit a Corvette at this range with at least 30% of your shots.
Now this CoF goes "down" (technically it gets smaller but it's not actually getting smaller, but for the sake of brevity I won't explain in detail here) to 104 meters at 2 kilometers from your target, shrinking again at 1 kilometer (the usual distance I engage at in Elite) to about 52 meters. Remember, these numbers are the diameter of the circle. If you can, fit a 52 meter across circle on the top or bottom of a ship, you can reliably hit it at this range, making most of the boxy ships rather easy to hit. You'll need optimal angles, of course, but a good pilot can still make use of this. It gets to a rather respectable 26 meter CoF at 500 meters - ramming ranges and some of the closer quarters fighting I've seen in space - which still leaves smaller ships to be a significant problem.
Now, I will admit; this isn't terrible, but when there are other experimental effects that perform more reliably, and whole other weapon classes that fight better in these ranges, and it also leaves you essentially wide open to being eaten by smaller fighters without some other weapons to pick up the slack, it is a very niche weapon. That niche being smaller, maneuverable ships fighting Corvettes and other heavy tanking ships.
Now, my request is to move the jitter angle down from 3 degrees (as measured by arc; 1.5 degrees from center) to 2 degrees. This still makes it challenging to hit smaller ships, but gives you a much better chance, bringing your 3 kilometer CoF from 157 to 104 meters, your 2 kilometer CoF to roughly 70 meters, 1 kilometer to 35 meters, and 500 meter CoF drops to a much more reasonable 18 meter circle. This would still keep the weapon in the niche - fighting larger ships while having them in your limited hard-points to bust shields and hull more quickly on an agile fighter - but also not ruin a fighter's day when he gets rolled up on by another fighter.
Another potential would be 1.5 degrees arc ( 0.75 degrees from center ); which would bring things from a 78 meter 3 km CoF, a 52 meter 2 km CoF, a 26 meter 1 km CoF, and a 13 meter 0.5 km CoF. Still niche, but much more usable, allowing you to even start to try to hit fighters with non-guided munitions.
An example of the current CoF (and how I figured out that it was 3 degrees Arc not 3 degrees from center for the cone of fire calculations )
[Yes it's sloppy; I turned black to alpha channel in order to superimpose the lasers over top of each-other, which is what's causing that "really bad CG" effect on everything. There's also a laser on the far side of the ship firing at the same time ]
TL;DR - It's not bad, but it could be better, and because it's as bad as it is, other things do a much better job of it, making it a useless upgrade on an a weapon already regarded as bad. Changing the CoF would help fix this and might actually cause these to be used more then never.