I agree with you on all these things, but subject to qualification. I think we need to be developing human spaceflight in parallel with robotic exploration, for the same reason that we don't do all our exploration on earth with telescopes. Air travel is orders of magnitude more difficult than sea travel, which is orders of magnitude more difficult than wandering about on land. I think there is no substitute for getting out there and attempting a wide variety of technological workarounds, notwithstanding the fact that many of these will be futile or fatal. The key plus for me of private or even semi-private space exploration is that failure or fatality won't mean a loss of political capital, compared to publicly-owned and managed space endeavors. Bluntly, we're more likely to discover better technologies if people are allowed to blow themselves up in the pursuit of same. On the last point, planetary colonization is one (remote) endpoint, if we can bootstrap it, but I think asteroid mining and the like also offers the potential of non-planetary habitation, which I find far more interesting. I remain optimistic about the possibility of other propulsive or spatial traversal methods, notwithstanding the limitations from our current theories of physics, though this is a statement about faith in technological progress rather than a specific hypothesis.