Some things like the Voyagers and Pioneers I think were very much worth it. But all we have learned from sending men into space is that it is really hard to keep people alive and functioning up there. With ever improving computers, the case for people can only be made on the basis of some romantic notion of space flight. I predict that the first attempt to send people to Mars will wind up with everyone dying a protracted and public death. That will put a damper on manned space flight for a while.
Space is just an ocean, men died to cross it too.
Now we call it the earth, and look to cross the stars!