First, it is extremely useful. The shag basic - shuffle basic is GREAT for lazy efficient dancing.
Second, I prefer to defer conversations about foot placement and articulation until learners have developed proficiency in body control, rhythm, pulse, lead follow, partnering etc etc.
While I think of shag as a “footwork” dance, I really want it to be approachable at first. It has enough inherent challenges about it (speed/athleticism) that I prefer to focus on helping new learners get some moves under their belt and maybe Getting the Scoot in Shag first too.