Walk starts and stops work well for running (notice, that it’s not really running, it’s more of a “tactical jogging”). Starting pose is the same, the motion is almost identical, the difference in end poses are small and disappear in the blend. In my Unity controller, I also play starting with x1.15 speed when in running mode.
Second reason is to avoid adding too much animations to the pack. It’s already 130 animations for $60. I think it’s a good compromise between usability vs. price.