I believe that deep bunkers are what often distinguish a great course from a pedestrian one. I suppose a bunker could be so deep as to be preposterous, but even bunkers that border on preposterous usually allow for a sideways or backward escape. When the devil's asshole was impossible to escape (which I believe it has been on occasion), it functioned as an unplayable lie and a re-tee - not the end of the world. Deep bunkers are often the defining characteristic and most memorable architectural feature of a great course. I can't think of a single great course with deep bunkers that wouldn't be "pedestianized" by having shallow bunkers instead. And, I really can't think of a great course that has shallow bunkers, although I am sure there are a few. (I know, Royal Ashdown Forest has no bunkers. But it doesn't have shallow ones.)