If your car doesn't bounce and you're not experiencing any abnormal tire wear such as cupping then why change them? Maybe your car was driven mainly on decent roads which would keep your struts/shocks from wearing out sooner. Springs wouldn't need changing either however they might eventually as they tend to sag as the car gets older. That could be a good thing if you want a lowered car without spending $ on new lowering springs .

I had the original struts and shocks on my car until I had 144K miles. They were still good from what I could tell. The only reason I replaced them is because I lowered it. Also, the roads I drive on everyday are very good and smooth roads.