VR Sickness is a form of motion sickness in Virtual Reality that affects 25-60% of the population. It is typically caused by exposure to mismatches between real and virtual motion, which happens in most VR Locomotion techniques. Hence, VR Locomotion and VR Sickness are intimately related, but this relationship is not reflected in the state of VR Sickness assessment. In this work we highlight the importance of understanding and quantifying VR Sickness in VR locomotion research. We discuss the most important factors and measures of VR to develop VR Sickness as a meaningful metric for VR Locomotion.