To me there’s things you can get away with on a “weekend car” or infrequent driver that you just can’t get away with on a daily.
If the shocks are stiff and don’t do a good job (or a flat out BAD job) of actually damping the suspension you not only suffer from a ride quality standpoint, you also lose traction and control.
Now, on a weekend car where you only take it out in good weather, stay out of traffic, and don’t do anything all that sporty a set of KYB’s will last forever and give you mediocre to bad performance the whole time, but it probably won’t matter.
On a daily, where you’re going to be exposed to more traffic, poor roads, weather etc the performance of those shocks could also mean being able to avoid an accident. And if you’re logging more miles, well, the odds of something happening only go up. Not to mention you’re logging more miles so improving the ride quality is going to make a big difference in how much you actually want to drive the car. Lousy shocks for a 20 minute drive once in a blue moon is one thing, lousy shocks for a 90 minute commute several times a week is another thing entirely.
This is actually a case of you get what you pay for, the KYB’s are cheap junk and the Bilstein RCD’s are a high quality shock that has a wide range of wheel rates it can handle very well.