May be you can explain me why is it important to link software requirements to the interface features that meet the requirements?
Because the goal of a design is to meet requirements. The matrix is a tool used so you do not forget requirements as the design progresses.
From you quetions, and your other posts, you seem to be performing software risk management without a clue of what software engineering is. Let me advise you that you are in danger of missing important hazards and hazardous situations because of this.
For risk management to function efficiently, it has to be a multi-function process where all stakeholders are involved. For example, if you did not design (which seems to be your case), you need to have the designer in your risk management team. He will be responsible for providing information on the design process. This is the same, for example, for usability..you need to have feedback from users, or even a sampe user, in your design team, to provide you with real world feebback on the interfaces of the software.