This seems more like an issue regarding enemy morale, rather than the zone of control system. Both the attacks always happening and getting hit meaning you stay put, are essential in making it so that neither you nor the opponent can move around at will once the fight has started. Limiting either would take away the need to be careful in how you place your units and take away a lot of the tactical depth the game has.
This is because without the attacks at max fatigue, a unit at max fatigue seizes to become a factor on the battlefield. They cannot influence the situation in any way until they regain fatigue and can safely be ignored, which takes away a lot of the danger that is currently always present in the combat and means that your choices have less risk to them, becoming less meaningful as a result. Same goes for limiting the amount of attacks, as after the first hit the unit can no longer affect the battlefield outside of its own turn.
In addition, being hit not cancelling movement means that it becomes trivial to move around in combat, as long as you can take the hit, meaning that you only ever need to worry about multiple attacks if you want to move somewhere. This makes not just the disengagement perks, but also abilities like shield bash much less important and reduces the weight of your decisions. No need to weigh the pros and cons of using shield bash or a regular attack on that unit that is tying down a mercenary needed elsewhere, just hit him and walk away with the other one if you happen to miss. A unit that has gotten surrounded by 4 enemies and starts to flee should also get ripped to shreds for it unless they get lucky, come to their senses or you manage to save them somehow. Getting surrounded is a major tactical blunder and correcting it should be difficult, not merely somewhat risky.
I think the zone of the control system itself is fine the way it is. It’s punishing in a way that encourages careful thinking, while giving you plenty of tools to deal with it. Softening it would take a way a lot of what makes the combat special and different from other games.