[ColinWright]

It can be done by robot, it several new abilities, it acts as a staging post for deep space missions, it lets NASA examine an asteroid close up and repeatedly, and it can be mined, again demonstrating abilities needed for deep space missions and for long-term possibilities for resource acquisition and management.

Also, why not?

[ddt]

I think the second reason you listed to be much more compelling than the first. It could be argued that the space race was about ensuring that the US had missile superiority over the USSR, but I'd wager a significant number of the aeronautical engineers and astronauts involved were much more interested in going to the moon because it was there.

[BrandonMarc]

... and heck, it gives us a reason to go back to the Moon ... or at least, send more probes, etc, there, which themselves might help give more reason to go back to the Moon.