The idea of AMBAC is built on real-world physics, but much of it is misapplied, misunderstood, impractical, or just wrong.
For instance, that Zeonic space fighter that was used to demonstrate the AMBAC concept? The maneuver wouldn't work as pictured - it starts by swinging its right "arm" forward, making the ship turn right. But that arm is presumably only about 20% of the ship's mass, so it wouldn't turn that far. And the arm doesn't keep turning, it swings forward and stops, so the part of the ship's rotation that was caused by that arm swinging forward also stops. For the ship to do a 180 using AMBAC, it would need to swing its arms around like a helicopter - basically, turning them into a big reaction wheel. This makes a lot of these "AMBAC structures" like wings and tails kind of useless, since they can't spin around. Shifting limbs and binders around could have some very limited benefit in maneuvering, but it wouldn't be this propellant-less reorientation from the space pod example.
Reaction wheels make sense for spacecraft because you can reorient the ship without using propellant - you just need electrical energy. It's great for spacecraft like probes or satellites that have a continuous electrical supply but a limited budget of fuel that must last years in some cases. It's a good fuel economy feature. Fuel economy is useful, but in a vehicle that must constantly deal with the possibility of being shot down, high performnce (making maneuvers more quickly) is generally more important than fuel economy.
There's a lot of the "science" in Gundam that, when you stop and think about it, is complete, total, absolute nonsense. Hell, the very premise of Gundam(or of most mecha anime in general) - the idea that a giant humanoid robot can fill any combat role at all better than a non-humanoid vehicle explicitly designed for that role(such as a tank or a fighter) is complete nonsense right off the bat. The human body, when you think about it, is a terribly inefficient design for an artillery platform, or any kind of airborne anything, or naval/underwater operation. Really, for just about anything combat-related on any kind of scale beyond infantry.
That being said, I totally agree that the AMBAC concept as it's presented is rubbish...which makes it a nonsense attempt at justifying a concept that was nonsense to begin with.
I think AMBAC may be an exaggerated and dated methodology to what gyroscopic servos can do in modern day aircraft or spacecraft that has been tested already in drone technology, etc. The tech in the Gundam universe is always being retconed and updated as things change in our own world and that's just part of how the franchise stays relevent and believable for its audience.
As mobile suits as practical weapons, it depends, as the ones made for ground combat usually can do the job of a tank, an attack helicopter, and some forms of artillery all in one machine and their ability to move unlike either of those other vehicles makes them useful. They also do not require a multiple person crew and are designed to make advanced tactical movements easier for a single pilot to pull off. For an army with a low amount of manpower and MS would be very useful, also drone AI units would be useful for supporting other assets as well.