As I understand this question, you are asking why you should discuss the importance of research that you are proposing. The reason for this is that your research will seem much more relevant to people if it seems to be connected to issues that are of great importance to leaders and other stakeholders.
While people sometimes characterize academia as an “ivory tower,” academics do typically want to be relevant. This is particularly true of social scientists since they feel that their research has direct applications to social problems that face our society. Because academics want to be seen as relevant, they should discuss the importance of the solutions to the problems that they are setting out. They should clearly state how the answers to their questions could be relevant to various stakeholders. If they can do this, they can establish that their research is useful and that people outside of academia should pay attention to it.
Thus, such discussions are important if an academic is to get his or her research to be important to people who affect public policy.