I think that your shocks/struts probably are in working order.

Bilsteins are more an upgrade/preference issue. I replaced my stock ones with Bilsteins at about 110,000 miles, but I live in Michigan, home to the worst roads in the known world. Many local roads are used by the OEMs to do squeak and rattle tests - better than they can produce when they TRY to make bad roads at the proving grounds.

Bilsteins are stiffer, but I think the ride overall is the same, except that the wheels really seem to stick to the road, like when you hit a dip on an off ramp or on a curve, the car doesn't feel like it will lose contact.

It's also a matter of getting used to it. If you drive another or more cars, then the responsiveness could be more noticeable.

I think the ride is still a little harsher than my C70 T5, even though I have 17 inch wheels on the C70 and 15 in wheels on the 850. Sidewalls also play a part, so 15 in wheels give a little more cushion than 17s or 18s.