One story to explain it: Space filled a psychological niche for people, which something else now fills. A logical thing for that to be would be the internet and computers. For some of us who are hard core futurists, we also have far-future aspirations like life extension and uploading to concern ourselves with. It's not that we've given up on space, but it is less captivating because it competes with other interesting things now. With less enthusiasm for the topic on display it has subsided to one of many interests, of great concern for a few interested individuals but lesser concern for the population as a whole.

Interestingly, launch prices continue to go down and the specialists continue to accomplish amazing things. It is possible that a diminishment of far-mode thinking about the topic has actually lead to better business and pragmatic decisions than would otherwise happen. Instead of expensive moon shots, perhaps we will get there faster because we have private companies making millions by launching communications satellites and developing less expensive rockets.