Dr Phil Harris is a Moon First space advocate and a published and acclaimed author. In his book Space Enterprise: Living and Working Offworld in the 21st Century, he goes into exquisite detail of the challenges and the bounties of industrializing the lunar surface.
In early January of this year Harris authored a special White House strategy paper [redistributed with permission] which recommended a pushing forward on the Vision For Space Exploration, or at least the Moon focused vision that came out of it. He makes it very clear that the reason to go back to the Moon is to get resources and reduce the national debt.
Now is the time to enlighten our nation's citizens of the vast resources to be tapped on the Moon. We could not only mine the lunar surface for valuable minerals and gems, but we could use its water and regolith to support lunar industrialization and settlement!
Those last two words are the only mention of settlement in the entire paper - so this is an economic argument and I feel the need to express my skepticism that such an economic argument can be seriously made at this time. Currently, the cheapest downmass from LEO costs $28,330 per kg. Although the price from the lunar surface would be much much higher than that, this is primarily due to a lack of in-space infrastructure. It's conceivable that strategically placed propellant depots with resupply from ISRU on the lunar surface could drastically reduce costs to a level feasible for lunar resource retrieval. More exotic cis-lunar infrastructure, such as Lunavators, could reduce those costs even more.
Harris also makes the argument that the Moon is the perfect place for all humanity's polluting industry, including power generation. This is an argument the Green movement could get behind: exporting the nasty side-effects of technological civilization to the Moon would leave the Earth to recover into a pristine reserve, without reducing the quality of life of the human population.
This argument is sound and reasonable. In response to the question: why go back to the Moon? Harris has a clear answer: industry and the wealth that flows from it (and settlement). In my words, the Moon is the future mine, and industrial park, of humanity.
If you look at mining practices on Earth, you will see it is becoming more automated, as is all industry. In a sense, Rio Tinto and other mining companies are doing Moon-analog training in central Australia.
"It sounds crazy but quite a few of the problems in space and in remote mining can be similar," said Gipps, from the Commonwealth Scientific and Industrial Research Organisation (CSIRO). "You don't necessarily want to have people there... so a lot of exploration on planets requires automated and remote operating systems, particularly automated."
Many self proclaimed robotics experts will insist that you'll always need humans nearby to fix the robots. I agree, but I define "nearby" differently to them. The Moon is, on average, 1.28 light seconds away from the Earth. The teleoperation workflow used to operate driverless trucks and trains, and sensor-fitted "smart drills" can also be used to operate repair robots. Highly articulate robots like Robonaut 2 can be on the Moon faster than a human return and can be operated to do any useful task.
These techniques are being perfected on Earth because they are economically valuable. Simply, it's cheaper to hire office workers in Perth to operate the equipment remotely than it is to attract and house on-site workers. If this is true for Australia then how could it ever not be true for the Moon?
If we want to make a sensible argument for why we should be sending humans into space, we need to base that argument around the future homes for humanity, not mines.