It may be useful for some raw materials - for example, osmium ($13,000/kg), rhenium ($2,750/kg), and iridium ($30,000/kg). All three of those are elements that

It may be useful for some raw materials - for example, osmium ($13,000/kg), rhenium ($2,750/kg), and iridium ($30,000/kg). All three of those are elements that are probably common in the Earth's mantle, but nowhere near the surface, and are mostly found in meteorites; all of them are used in high-performance alloys (high-temperature, corrosion-resistant, etc.) Doubling the world production of any of these would greatly reduce the prices of aerospace engines and electronics (iridium is used for crucibles growing high-quality semiconductor crystals). And that's easy, because the quantities involved are so low - under 1 ton of osmium per year, 10 tons of iridium, and 40 tons of rhenium. There are other materials like that. It's all about searching for the competitive advantage, the materials that can't be found on Earth in reasonable quantities. All the nickel and iron and titanium will indeed probably stay up for in-space use.