Force on the footpegs should not be wasted driving you back into seat, but in going into driving your non-paddling side hip forward. Imagine that you are sitting on a phonograph turntable – your hips rotate in the seat pan. Your rotation should go all the way down to your butt in the seat (if efficient forward stroke is your goal). That said, the wide, splayed foot/leg position required by many recreational SOTs greatly hinders torso rotation (but provides stability). A close knee/foot position with slightly bent knees, as performed on a surf ski, offers the most torso rotation (but limited stability). A lot of kayaks don’t let you adopt this position, or require modification to do so.
That said, leg drive / torso rotation can be overdone (although most people usually don’t do enough, or don’t do it efficiently – in my teaching experience), and visually it appears subtle, unless perhaps, if you are sprinting.
I also have problems with a lot of the flimsy plastic rails and footbraces on many kayaks, when I demo them. Some brands feel like I could easily snap them off if I was going 100%.
Greg