Many people say they see no reason to go back to the moon and want
to go on to Mars without a lunar program. However, it is probably
easier to make a case for going to the moon than for keeping the ISS.
Remember, the moon is not a small place, it is a WORLD. We have not
seen much of it and it isnt just a pile of uninteresting rocks but an
entire world of strange things and places to be explored. It probably
has vast lava tubes that can be used for habitats much easier than
making large habitable spaces in orbit. We still do not know if the
moon is geologically a "dead" world but observations of lunar transient
events hints that it isnt.
The moon has resources; granted we dont know about most of them but
at least we know about the composition of most outer regolith and of
the probable existence of water ice near the poles. With the water
that was delivered by comets, is there also abundant hydrocarbons from
the comets? The gravity of the moon along with its lack of atmosphere
is a real resource by itself for various manufacturing processes.
Imagine being able to make huge electron beam evaporated coatings
unlimited in size byt he size of a vacuum chamber while being able to
count on gravity to hold things in place.
Having a world like this so close to earth is really fortuitous and
I can see far more reasons for going there than going to Mars. Arguing
that "we've been there and done that" would be like someone arguing
that once Columbus did his first voyage and found nothing of importance
that Europeans had "been there and done that" so there was no reason
for further voyages.