If you're fitting rusty parts to the car they'll just get worse which isn't good if you have no intention of selling the car, I'm having to replace my stock reas suspension shocks because the rust is that bad there is a possibility of them leaking.
I'm taking the opportunity of painting all the suspension parts and fitting nuts/bolts that won't rust, infact every part I'm fitting anywhere on the car will be treated to last which the car manufacturers don't do.
I'll see the benefit when a part wears out and I won't have a problem taking them apart, I don't want the car to deteriorate like every other car on the road.