I wouldn't be so quick to dismiss this criticism. I've had a similar initial impression as the OP, but eventually got used to it. It does improve once you learn to keep it in the blue zone, have better thrusters, get a generally more maneouverable ship. But first impressions do matter, and I feel Frontier isn't doing ED justice here.
I generally really dislike the "for game play reasons" discussion killer. I try to reason within the confines of the game world, why stuff works the way it does.
Regarding the yaw rate, if you use the external debug camera and inspect the ships, you can see that all of the maneouvering thrusters are either dorsally or ventrally of the ship. And if you watch which thrusters fire, you'll notice that both dorsal and ventral thrusters most close to the lateral line of the ship are being used to yaw. And since these thrusters provide mostly dorsal and ventral thrust, this isn't very efficient for yawing.
The ship designers could have added lateral thrusters. They could have instead used
Control Moment Gyroscopes as a far more efficient mechanism for yaw, pitch and roll. But they didn't, and so we have really slow yaw rates. At least it's explainable within the confines of the game world.
And the improved manoeuvering in the blue zone make sense, if the reactor could not provide power to all engines and thrusters at the same time. Much like the power capacitor can't provide full power to all systems. So if you provide max (forward) throttle, there'd be less energy left for the thrusters, but that's ok, since you'd mostly want to go forward. If you throttle back, there's less load on the main thrusters, so the manoeuvering thrusters have more ooomph.
While this would explain the observed behaviour, it leads to another inconsistency: given zero throttle, the pitch, yaw, roll rates as well as the translation rates should be greatest, as there's full power available for the maneouvering thrusters. For now I can't come up with a good explanation except maybe: Some bureaucrats in the "Spaceship Standards Consortium" have decreed this behaviour for safety reasons and thus it became a standard for flight system computers (and it's actually those computers limiting maneouverability, not some handwavium nonsense.)
To me (and maybe others) this feels artificial because the effect on manoeuvrability is not based on the throttle setting (and thus engine output), but instead on the magnitude of the movement vector, ie. the ship's total speed. This is especially noticeable once you disable Flight Assist.
You could argue that lower rate of manoeuverability at low speeds is desireable because it's more likely that you'd want precision movement instead of raw speed.
Frontier stated they choose this flight model for it's entertainment value and because it leads to more interesting dog fights. So instead of circle strafe fights we got circle chases... tomayto, tomahto.
