Having a sustainable transport scheme is a necessity in moving to Mars. I don't think anyone is naive enough to think that in practice transport is the hardest problem. But it's psychologically important - without transport there is nowhere to go. Either we become multiplanetary or not - I don't know - but if we become multiplanetary then transport is a necessary step. Building the transport scheme from economically self sustaining processes is only for the better for the robustness of it.

The fact that something is marketed does not diminish the utility of a thing.