The polyurethane bushings have been very popular in the performance car market for at LEAST 20 years that I know of. They don't work the same as the factory ones, they provide less deflection of the suspension components, (thus their popularity in the performance car market) and possibly a little louder, harsher ride (the trade off for performance.) But they work very well. The factory did very little because it was the best right thing to do, if it gave even marginally satisfactory performance and was cheap that is what they were after. Just good enough to not have too many warranty repairs, and good enough so the regulars didn't defect to the competition. After that is was just money that dictated design.
