Manned space travel at the current time makes no sense scientifically, politically, economically or for any other purpose that I can divine. 20 years from now, that may no longer be the case. But at the current time, the cost is prohibitive and the benefits are nil.
That's a reasonable conclusion. Current NASA plans don't seriously address the R&D required to enable molecular nanotechnology (MNT), that could eventually open the door to new possibilities for manned space hardware development and operations.