[1] well if we want government to be involved then yes, we do need a political reason - that's the way government works
[2] no one said that
I look at manned space flight to the moon and I see it effectively finishing with the cold war, why is this do you think??
In regards to the future for NASA, I agree, I doubt it will disappear entirely; however its functions will slowly be adsorbed into the private sector.
I'll point out that there is currently no formal plan to return to the moon