There was a time when going to the Moon seemed a normal thing for the future. This was even considered without any knowledge of He3, of ice on the poles, of permanent shadow or permanent sunlight.
Even huge solar pannels on the Moon or telescopes are not old ideas.
The Moon wasn't going to be exploited for what it had, but always, there was a Moonbase.

Now, this is been fought by those who support Mars.

But Mars also had a different prospect. Terraforming Mars isn't that old a concept, using its resources is even more recent.
There was a time when Mars was thought to have a thicker atmophere.
Even today, this notion still persists. Not for the today Mars, but the ancient Mars.
There might still be hope to find the holy grail of science: extra-terrestrial life on Mars.

But nobody can be sure that its discovery (if ever) will incite lots of money to be spent to send manned expeditions.

I'm pretty sure unmanned landers will yet again change our perception of Mars, even before we can become convincing enough to incite governments to send expeditions out there.
And I'm not convinced Zubrin and the Mars society want a long term presence on Mars. They badly want to go there and bring up ingenious ideas to make it cheaper and faster. Making it cheaper and faster are the best way to go there for the flag and the footprints. But if there isn't a convincing long term Mars project, then it's one flight and it's over. (It's like Iraq: preparing for war but not for what comes after: peace).
Also, there is another problem: we might not even know why and how we can stay on Mars before we've been there at least once, to find out.

Kind of like the Moon: gentle hills, one color, too bright or too dark and anyway far too dusty. No gullies, no caves, no cliffs and dust all over.
Why bother with a Moonbase? Astronauts staying inside a moonbase won't be exploring so they might as well stay on Earth and remotely control robots on the Moon.
But Mars...There are three areas we know:Chryse, Utopia and Ares vallis.
All of them are completely covered with rocks, rocks everywhere...
On the Moon, rocky areas were avoided by the Rover and on the Moon, the gravity is lower than on Mars, but so far, we've seen fewer areas completely covered with rocks (thus inaccessible) on the Moon than on Mars. In fact, the irony is that the gentler slopes on the Moon made landings safer than scientists thought in the begininning even if they made the landscape more boring.

Raoul