Expensive yes, but far from pointless. We are going to travel to other planets at some point, why not start building the infrastructure for that now? imo it is a much better use of resources going to another planet and having the people sharing their experience with us instead of sending robots to take pictures & drill rocks, even if all we got out of it was inspiration.
Besides we are going to need a new planet to occupy in the not to distant future if we keep up our current pace.