I believe I understand RL's rant.

I wonder why we're interested in space.
When so many argue that only private companies can make us dream, the problem is : private companies don't want to make us dream, they first want to make money. And as long as short term profit is the rule, there's no hope for great space adventures unless there's a political commitment. China has a space vision, because it doesn't care about short term investment. The Soviet Union had a vision as well and in the 60's the US had a vision and NASA was created to centralize the forces needed for the Moon goal, which wasn't at all something private companies would have dared to do.

But why go to space?
Sorry, but I'm not interested in colonies (because in colonies, we too often find the same problems as those we tried to escape from).
That's why I'm not too impressed by Zubrin's arguments. Now, if it's about creating another basket in case the Earth gets hit by an asteroid, this can be more easily done by a systematic asteroid detection program (even the small rocks) and also studying means to divert the rocks from their path towards Earth.

What fascinates me is the fantastic knowledge we get from what's up there!
That's why I love space: it's a place to explore.
The Moon has only been visited is 6 places.
Mars also must be explored.
However, it turns out we learn a great deal even without sending humans out there.
Guion Bluford once said to Wubbo Ockels, a little before STS61A-Spacelab D1 landed, to enjoy it while you're up there because here, you're richer than the richest man, but back down, you're just another guy.
Astronauts are very privileged persons (Cady Coleman told me that in Paris). But in the ISS, it looks like they're not really very useful for advancing science as their job is mainly about turning buttons and checking an experiment and turning it off, afterwards.
The irony is that prctically everything humans can do in space, can be done through telepresence and this all the way to the Moon. In a way, there's no need for humans in space, for scientific purposes, other than studying humans in 0 G , but this is only valid if they're going to stay a very long time in space.
A very long time suggests going to Mars. But it's not just the trip, it's the boredom of the trip, the solar radiations, the low Mars gravity. But in my view, Mars is to be explored, not colonized. So why send humans if robots can do an almost as good a job and for far less money? (Well, we should wait until the trip can be shortened).
We're never going to see something similar to Apollo in our lifetime, so we might as well enjoy all the information provided by the unmanned satellites or probes like HST, the Mars probes, Cassini, etc.. It is much much more than we got during the Apollo flights! Mariner 6 and 7 (right after Apollo 11) saw only Craters on Mars because they could only fly by the Planet and the camera was pointing to the south, when nearest).
We do get much more science from space than we got yesterday But do we recognize this?
If a telescope in space (away from Earth, where SIRTF is now or Webb will be) is a better solution than on the Moon, then ok, let's not go back to the Moon if it's only for astronomy, but the Moon is there.
Jack Schmitt came up with several ideas and reasons to go back to the Moon. They're probably too farfetched or premature, but he's certainly trying to advocate the Moon.
I also think the Moon is important and we have come up with reasons to return back there. Some didn't last long and some are waiting perhaps in a student's mind for a thesis at his university.
The Moon shows us the history of the solar system in a way the Earth cannot. The Moon is the nearest other world , besides Earth. The Moon relates to every culture on Earth. The Moon is extremely different from Earth and so many things are hard to obtain on Earth because of what's here and could be easier on the Moon. Whenever issues such as temperatures, vacuum, low gravity, solar energy come up, the Moon can become part of the argument.
The way we're going to use the Moon or Mars or the other worlds depends on knowledge. We cannot anymore perhaps share with those who weren't there, the excitement we felt when we saw those human representatives strolling on the Moon.
But they brought back knowledge and everything we do is based on knowledge acquired in the past.
Knowledge doesn't disappear as quickly as emotions , luckily. And knowledge is shared worldwide, while only a few humans go there, what they found can be teached all over.
Knowledge is what matters indeed.

Raoul