I think we really need to look at this historically, the first sailors used smaller ships which were only able to follow the coast or travel short distances up rivers, further development in navigation and hull designs allowed them to cross the great depths even further. I think we are still in the Raft stage of space exploration, although it is a great idea, I think we need to work on those little steps.

Getting back to the moon and/or perhaps chasing asteroids seems much more practical at this time I don't think colonisation of mars will ever happen unless we gain the capacity to build bigger ships in orbit of earth, it just costs to much to get things up there. If we can solve the issue of getting basic materials and manpower into orbit and then set up supply lines that do not involve earth then we will be ready to start making caravels instead of rafts.