because the pieces are so specific (fit only in such a way to make a space shuttle or pirate ship or...),
I think this is completley untrue. Just because the piece is the bottom of a pirate ship, doesn't mean it you can't use ot for something else. Most ofthe special pieces are used in differnt ways in differnt sets. I have one child who tends to make the sets to the plans, and one who will make the set to the plan once, break it down and invent , invent , invent. over and over and over.