The shocks completely failing with a leak, is a bit atypical. But usually, by 90k miles or even less, your shocks should still be functional, but far from ideal; and you will experience a ride improvement if you replace at that time or even earlier. I changed out my shocks around 60k miles to bilstein HDs and regretted I didn't do it sooner.
Still, your expectations are a bit skewed as time is a factor. It's a 12 year old car. You need to expect that you got the short straw and got some bad luck on something. It is the same boat as a guy who gets a sticky brake caliper or the starter going out or something else failing, it happens.
The other way to think about it, is the sooner you replace, the sooner you can enjoying the improved car; rather then sticking it out with the crappy ride that you probably didn't even notice. If the new shocks last as long, you are good for another 12 years.
You should change the shock mounts at the same time. And get an alignment when all your suspension work is done.
Last edited by raytseng; 07-05-14 at 09:28 PM..