From Krauthammer's: It is not only pointless to continue orbiting endlessly around the Earth; it is ridiculously expensive and indefensibly risky.
The problem is: going to the Moon or going to Mars are as if not much more risky!

If one is fed up by turning around the Earth , one will get fed up inside a Moonbase and also inside a Marsbase.

That's why exploration is emphasized.
That wouldn't necessarily require bases.
But one can argue that landscapes and soil properties and geological characteristics are very much the same all over the Moon and therefore it would be pointless to explore more only to find the same all over it.
Mars has different geological features, two very different hemispheres, but Mars is so far away not only in distance but especially in time to get there and back!

The Moon's advantages:
It's the closest other "alien" world to Earth.
It is extremely different from Earth, thus worth investigating what we can't find on Earth.
It can protect astronauts from Solar eruptions ,much faster than anywhere above the Earth's Van Allen belts.
It won't require new propulsion methods.

Mars' advantages:
It has lots of the characteristics required for life to have evolved.
It can sustain , with in situ raw material, astronauts on the surface.
It has lots of different geological aspects worth exploring.
It's atmosphere can be used.

Raoul