Perhaps

though I think that is part of it, its also why the majority of new C5s have coil springs. More simple to appleal to more people, mainly reps. No doubt it costs a great deal more to fit hydractive suspension rather than a few bits of bent spings, especially as its really a Peugeot.
Should engine failure occur the Xant etc does have brakes, however limited. They should also not be towed as the brakes are very very limited, virtually dont work with the engine off. Much to my neighbours dissapointment who rolled his new Xantia estate back on his sloped drive, pressed the brake and shot straight through the closed garage door, damaging the brick pillar. So I can see why that was designed out.
Its not really complex as every normal car has brakes and steering seperate, all your adding is a electronic pump for the suspension. I like it, I guess some people might favour the hydraulic powered brakes as they are more like a switch, though dont actually offer any other benefits and C5 brakes are far more powerful and have a lot of bite anyway. Steering, well neither set up is really built for communication, I can't tell the difference other than the C5 doesnt have heavy moments as the car is depressurised, pumping up etc. I also like the electric suspension pump, its so much quicker. Though this does sometimes make me forget to let the XM or Xant pump up before driving off.
With all, XM, Xant and C5, they pump up beside you when your filling it up with fuel. I like that!
For me, the perfect Citroen would have C5 style hydraulics and a symplified Activa system. As the C5 is a huge wafing car, pretty much the same length as an XM but quite a bit wider, its not a sporty thing, so something a little smaller fitted with the above system and the 160bhp version of the 2.0 HDi, would be ideal!
If the DS4 had hysractive suspension with a more simple ARCS system, that would be very very interesting. As it is on its primitive coils, its not so appealing.