This topic was very much discussed on campus during my grad school days (10 years ago now). I'm quite sure that Dr. Gary Flandro discussed it with many people a

This topic was very much discussed on campus during my grad school days (10 years ago now). I'm quite sure that Dr. Gary Flandro discussed it with many people at great length. But then, that's one thing he's always done -- figure out how to get to new and exciting places in the solar system. He was very much in favor of using the Moon as a base for expansion into the rest of the solar system for exactly this reason. Once you set up a beach-head there with facilities for extracting materials and manufacturing goods, it's much easier to launch onward into the rest of the solar system. This, I recall, was a major theme of the Quick-Goethert lecture that Dr. Flandro gave in 2005. It was a great pleasure to attend that lecture. So yes, just from that one example, I'll grant you that people discuss this sort of approach all the time. Dr. Flandro certainly wasn't the first, even then.