Your question is why does KDSS use accumulators? First: It is my understanding of the diagrams that the valves are inline between the accumulators and pistons, so KDSS doesn't engage them above 12mph, so any speed above that they are closed off by the valving. Closing by valving fixes the position of the piston - meaning THEY DO NOT CYCLE during 99% of highway driving. This is likely for longer service life. If they aren't moving, they aren't wearing as much.
Below that speed it takes a bit of the edge off by dampening the system. This probably means longer service life due to reduced instantaneous loads, and probably the ability to use somewhat smaller and lighter hardware. However these explanations are called into question by the non-use of accumulators at higher speeds where the highest forces will be experienced. It may also have something to do with imperfect manufacturing tolerances and absorbing fluid volume variances. It is also possible that there is a dissimilar piston stroke/bore and they are necessary to accommodate this.
Accumulators likely do nothing measurable for shock absorbing in the suspension. In fact I'd bet the moment of inertia of the sway bar about the bushings has a greater effect than the accumulator allowed movement of the KDSS piston. You could probably just bleed the system poorly and have the same effect - but that's not easily repeatable. In either event both are going to be negligible noise in comparison to the actual dampening provided by the aptly named "shock absorbers".
I'd be happy to do the calculations when I have some time. But we're going to have to agree on the bushing friction - as that's a limiting factor on any dampening force actually transferring from the piston to the a-arm. I really don't know what that measurement is. It should ideally be zero, but it's some non-zero value and is going to be somewhat inconsistent between vehicles. Any proposals?
If you question is why they made the bar mount mobile rather than use a BMW/LR style twist inducing mechanism, it's probably sixes. Neither is inherently better. Some just physically fit into an existing platform better. Otherwise I don't think there is a compelling case for one or the other. It's clear why there are advantages over a disconnect like Jeep uses. The Jeep version is simply cheap. If there's ever a question about why Chrysler does something - the answer is always because it's cheap.
