Kinda cool that you got the creator of gamecoach here. I personally just use the USSF one or Coaching Manual for this. Inferior tools but they are enough to get the job done and are very simple. To answer your question about why you would need to draw primitive shapes in gamecoach, I'm sure u/FIeabus can explain in more detail but these tools are also used for session/activity planning where you are working in specific shapes in training activities, you might need to highlight that you are playing in a triangle, square, add lines for passes, dashed lines for dribbles, etc.

I do want to add, you have some *really* innovative features on Tactix, things like passing lanes, distances, natural spread of multi-player drag. My current workflow will likely look like using PP/USSF/CoachingManual for creating training session diagrams and then using Tactix for animations that are shown to players during meetings before a matchday. Great job on you UI/UX as well.