Planning the initial trips to be one way makes a fair amount of sense, but what little I’ve gleaned about Mars One doesn’t really seem entirely based on the premise.
The media spectacle concept: Stepping up to go to Mars for the rest of your natural life seems an objective diametrically opposed to becoming a reality TV star. 2+ years cooped up with 4 people and your only outside contact is people who need you to “perform” for a TV audience to keep the funding rolling in.
Over-enthusiastic mission-to-mars proponents like to draw an analogy between, say, Columbus and potential Martian settlers. This seems to be an extreme exercise in “unhistory”. Unlike Mars, the New World was the same distance from the sun, with the same life-essentials such as gravity, gasses, solar radiation levels, tolerable temperatures, pressure, soil, exposed liquid surface water, familiar building materials, compatible food sources, etc. Most importantly, it was the indigenous peoples that helped keep settlement from having a much higher cost.