I think most people's responses to the idea of mutual respect as the ethic of justice is similar. Most people's first response is, "Respect must be earned." There is respect that must be earned, but justice lies in the respect that every human being is due merely by being a fellow human. Also, people get hung-up on the mutuality part. For justice to be present all must be respecting one another in the minimal way, but it does require that each person unilaterally engage in respecting others. The point I'm laboring to get to is that formally acknowledging mutual respect as the ethic of justice and its implications for society would refine it over time as a concept for people, as you say.