If the purpose of space exploration is to someday inhabit another world, then using robots instead of humans is counter-productive. Sure, one or two unmanned vehicles to start is ok, but the short-term goal should be human visitation. Only then will we begin to understand what truly needs to be done in order to reach the ultimate goal of interplanetary habitation.
Along those lines I have often felt that the space station itself is somewhat counter-productive. Why not build a large base station on the moon and develop lunar resources? At least that way we're working towards true migration onto other planets. I believe the space station could be used as a "bus stop" where travellers would arrive by shuttle aircraft and then transfer to an interplanetary craft for transport to the moon. The opposite would occur on the way home. Two vehicles, each suited to its purpose.