Why do you need to have humans alive who walked on the moon? It was an interesting experiment at some point, but there's not much to gain to do it over and over again, unless you plan to have a permanent human presence there.
Reaction from children is along the lines of "this is so cool; I want to work in space stuff".
In many ways you make a very valid point, the ISS is what we've been up to for the last few decades rather than going back to the moon and the research coming from it will be essential in preparing for longer journeys. But for all that I stare up and marvel at it passing overhead some nights, it just doesn't hold the same mystique of say the moon or further afield.
Even GNU is something inherently supranational.
This should teach us something, I think.
I could understand there being no one left who has walked on the moon if we'd been concentrating on the next challenge, i.e Mars. But that's obviously not what happened.
Ultimately I think it would serve as a marker of our collective lack of imagination over the past 50 years to explore, perhaps because the costs weren't palatable relative to any resources we could hope to exploit.
Honestly it's not a lack of imagination - Plans to explore Mars and even other planets existed back in the 60s and 70s. Space Exploration was very much a byproduct of the Cold War - developing rockets mean you developed the ability to produce ICBMs as well to strike with nuclear heads anywhere, anytime, and Space programs were simply the tip of the otherwise military Iceberg.
They also served as PR material to give a positive image of rockets development, while actually most rockets are made to nuke the Earth multiple times.
Now, the tensions we had during the Cold War are lower, and the need to develop new rocket tech has decreased, and you get a Space Program on diet.