Some parts do wear out, and springs are on that list. Some original parts are too damaged to repair, particularly when good reproduction parts are available (think melted or shattered consoles and dash panels, or fiberboard door panels that got soaked). Other parts just aren't safe anymore, like original suspension bushings, hoses (AC, power steering, radiator, heater, brake and fuel lines) sun damaged seat belts, heavily rusted suspension and brake components, and pretty much any old fastener. The ones to keep are the ones that are in restoreable condition, or parts that are/were rare, like good wiring harnesses, power window parts, rear defog parts, convenience group parts, that sort of thing.
