I own both a 124 & a 210, and previously had a 123. I very strongly disagree that quality was taken out of the 210. It is very solid and well built. What is different is that the 210 was designed to be easier to build, hence lower cost. This does not imply lower quality, simply more intelligent design.
As for removing cost, this started on the 124, relative to the 123. Let me give a few examples. The 124 has a strut type front suspension, where the shock absorber also serves to locate the top of the steering knuckle. This is just like every cheap Japanese car on the road. The 123 used a more complex and more expensive upper/lower control arm setup.
The 123 brake system used dual piston calipers on all four wheels. The 124 - at least the pedestrain versions - use single piston sliding calipers on the front, just like every American car out there.
As for 210 vs. 124, there are cases where cost was added back into the car. For example, the 210 went back to an upper/lower control arm front suspension. The 210 uses cloth covered trim on the A,B, & C pillars inside the cabin, where the 124 had just plastic. So it goes both ways.