for me its all the unique pieces they keep adding

Older lego moulded unique parts only when neccessary and tried to use them in other sets too when possible, and the rest was just repurposed, like the new lego harry potter sets having dedicated wand pieces molded just for it, which skyrockets the price of an already expensive licensed set, when normal lego sticks, like the ones they've used since 2000s, did the job more then well enough.