The original point was competing with the Soviets and generating national pride, sure. The point now would be to get practice with the harder problems of survival in space, as a trial run for the marathon that is going to Mars. Every time we as a nation do something that seems audacious, we raise the morale of the nation and energize the populace to work harder on pretty much everything else. We could certainly use a shot of national pride to the arm after the events of the past decade...
USSR was not moon rock-poor, it had a reasonable amount of moon rock extracted by automatic space craft (more precisely, space craft not inhabited by humans). The point of reaching the Moon is different, it's to spark the imagination and inspire. And one of the reasons the USSR collapsed is, btw, the ideas it was based on were not inspiring any longer (an understatement!)
USA: 382 kg
USSR: 0.32 kg
Recovered from meteorites: 48 kg
But that's from Wikipedia, so you can add a few grains of salt to those figures.
One of the main reasons the moon missions were cut short is because the public lost interest, just as they did with the Space Shuttle. The inspiration argument only gets you so far, and we've been that far already.
