"I assume the thing with gliding is it gets your feet working being having to be much more coordinated?"
If you fly a powered aircraft properly, you should also have your feet "working", not only to counteract adverse yaw (like in a glider), but also for the various effects caused by the engine and propeller - something you won't get in a glider. The only difference is that the average spamcan can be flown shoddily without correct use of your feet, and lead to laziness and poor piloting technique if a student isn't taught what to look for. In basic terms, the nose should stay where it is when rolling into or out of a turn, and everything is kept coordinated.