Suspension Component Wear: To What Extent Function of Age?

[shertex]

On my 92 300D, I didn't have to do my lower ball joints until about 175,000 miles when it was 14 years old. But, on my 91 300D with only 88,000 miles, they're starting to creak...but, as it rolled off the line in Stuttgart in 1990, it is a 20 year old car.

So, do some suspension components tend to go bad "early" because of age (due to rubber drying out, etc.)? I'm mildly disappointed that I'm having to do some of this work at relatively low mileage...but perhaps it's to be expected.

Thanks.