I'm not so sure. Beside the gelological aspects, a well supplied lunar staging area could launch a much heavier payload because of the Moon's lower gravity, thus affording a longer manned presence on the Martian surface. It would also effect a more efficient return as the vehicle would be less massive than one that would otherwise have staged from Earth, yet carrying more sample returns given again the lower launch requirements in Mars lesser gravity.
Yes but the moon is so far away for all of that. I suggest that if you start to consider all of the logistics involved for either one of those ventures with our current technologies (especially propulsion) it becomes not doable in the next 30/40 years or so.
I agree. Any sort of ambitious manned presence in the solar system would be greatly facilitated by a moon base. If it seems too expensive, that only emphasizes how much is required for such an ambition. It really is the logical step.
Scientifically, there would be great benefit in doing radio telescopy from the moon, both from the far side, to avoid interference, and from the rim, to establish Very Long Baseline Interferometry.
Meanwhile, I don’t see why we don’t launch lunar rover probes to do sample return and detailed exploration. There has been a spate of orbiters of late, so why not keep that ball rolling?