Every binding has springs. That's how they release. The spring presses against a surface with a raised edge, over which the mount must pass for the heel piece to drop and thus release you. Think of a car resting against a speed bump. Apply a bit of accelerator and it wont go over. Apply a lot really quickly and the car will roll right over the bump. In the binding, the tighter the screw is the more pressure that's required to release your boot. On the Markers its visible presumably for aesthetic reasons. I can't think of any other binding with an exposed spring. And I can't think of any technical reason why an exposed spring would be advantageous, beyond being able to see any fractures in it.
Sparknotes: Griffons are sick....get them.