As someone who is involved (peripherally) in the "New Space" movement, IMHO the first purpose of space development will be the availability of new resources and technologies. An economist a couple of years ago predicted that space development would have the potential to increase the standard of living of everyone on Earth by a factor of 10. That seems optimistic to me, but a reasonable goal. One popular example (see Planetary Resources, Inc.) regards the availability of Platinum, which is a very useful industrial metal, but is unfortunately $1300 per ounce. Platinum mining is expensive, dangerous, and disastrous both ecologically and socially. This greatly restricts is usefulness although it is used in those expensive catalytic converters in your car - that's why they're expensive. The best astronomical physicists believe that some of the Near Earth Asteroids contain single-digit percentages of Platinum. If this is true, then a 100 meter asteroid would contain a dozen times as much Platinum as has ever been mined. Retrieving this material to Earth could drop the price to between $10 and $100 per ounce, and this would still be economically viable for the company to process in space and ship it down to Earth.
There are many other examples. Technologically, the range of industrial processes that are presently either expensive or impossible on Earth due to gravity and air, that could be done in the high vacuum and microgravity of space is broad but it is likely that an order of magnitude more new processes that have not even been envisioned yet will be discovered or invented. Orbital production of high quality integrated circuits might well be one - one of the most expensive aspects of IC manufacturing is the requirement to build a huge facility and maintain a high level clean room environment. In space that could be done with not much more than a bit of Mylar.