reply to post by FX44rice
Simple question: Simple answer: Money!
Funding slashed (a little thing known as 'Vietnam') and a down-sizing to 'ride-out' the (thought at the time) temporary reductions in monies.
Decision to use the slack time to focus on un-manned robotic exploratory missions...cheaper, amassing data, to further help any future manned
missions.
(There is a sub-set of theorists who maintain that there is an entire "Secret Space Program" being run by 'black' funding via the Military, and
that NASA is just the civilian front).
Further, the Politics of the 1970s were volatile. I think there would have been tremendous opposition and possible de-stabilization if the USA had
gone ahead with a planned Base on the Moon, without International co-operation.
Longer-range manned missions have an increased exposure danger....and many technical hurdles. Again, years of LEO experience helps to hone skills and
learn from experience.
In aviation, there were pioneers...and sometimes decades for technological progress, usually spurred by outside forces (WWI) and (WWII), for
instance.
The manned Lunar 'flights' were risky, but a calculated risk. Equipment and personnel were tested tens of thousands of times.
Long-term exposure, however, to man by Solar radiation outside the Earth's protective magnetosphere is still being studied. By long-term, I mean
months and years, not just 6 to 8 days. In fact, Apollo was lucky....there was a large Coronal discharge in 1972 that would have been a danger HAD
there been a mission in space at the time. The CM could have been rotated to use the heatshield and the SM as shielding, IF it had happened during a
mission. In theory. Still, other than a dose of extra radiation, it certainly would not have been instantly lethal, but cumulative over the lives of
the people exposed.
Now, given sufficient funding, International agreement, and current technology, the most logical place to found a permanent Lunar base would be at one
of the poles. Why? Because it provides the best protection from the Sun, there is likely water ice there, and it is a good 'central' location for
any mining operations that could be conducted during the two-week long Lunar 'nights'. AND, the tech would be adapted to deep cold, and would not
have to contend with the vast temperature changes that are encountered at, say, the Moon's equator.
Now, having given a 'freebie' that amounts to, really, my opinion, I hope others will chime in with more ideas. Ultimately, though...there may well
be fights over 'land rights'. International 'Battles Royale', so to speak.
This is going to be a LONG story, likely generations in the making.
(Don't forget, a certain minority opinion, also, that posit an ET presence already on the Moon, who didn't want the company!)

So, sometimes....we have to entertain ALL opinions. All are welcome; we will see which stand up to scrutiny.