Very good points being made.
It's very simple; it's the ability to recreate the recorded event.
The sound design for the stellar gunshots in Open Range, the structural shaking of the Pod Emergence scenes of War of the Worlds, the impending doom associated with the fight scenes in The Incredible Hulk, all span the transition for all of us from normal hearing gathered by the pinna, and the physical sensation our body encounters with the lowest frequencies. Whether synthetically derived for effect, or an actual explosive event recorded for accurate portrayal of the weapon, the initial wavefront and subsequent frequency characteristics of the recording are experienced both by the individual in person, and by the enthusiast in the HT.
What we strive for in playback is no different, and actually quite similar, to what one would be experiencing if exposed to the effect first hand. Bombastic yet precisely accurate explosive wavefronts washing over your body, experienced in a viscerally, auditorily, with every sense one possesses. Room shaking infra-sonics, guttural LF and enough mid bass punch to elicit fear. That exciting sensation is exactly what the director intended.
Point being, I've read the physiology of human hearing, and the technical limitations. I've also read the actual testing of the finest infrasonic transducers availed to the industry, and how those frequencies are perceived as distinct tones,...differentiating that aural result specifically from the transition to more of a physical sensation. Bruce Thigpen, Eminent Technology, has conducted these LF/ULF audibility/sensation experiments.
I'm anything but an expert in infrasonics, however I've read material extensively, even conducted my own experiments of my own. My experiments are limited to distortion components, primarily structural, inherent to a wood-framed listening room encountering 125+dB of LF/ULF (peaks @129.5dB). Even with that capability, I easily need additional headroom for accurate playback of the realistic effect associated with contemporary motion pictures. Try to playback the final big effect in How to Train Your Dragon, full spec without encountering any system limitations (clipping, bottoming, distortion non-linearities) at realistic reference levels. It's quite demanding on everything from the circuits feeding your amplifiers, the amps themselves, the drivers, and finally the structural components of your HT. These broadband effects gobble up every inch of capability if played back at intended levels with no high pass filtration.
The LFE spec is 3hz-120hz, each subsequent octave downward, requires a 4x displacement (4x drivers, 4x power) from your subwoofer system to maintain a given SPL (16 times the capability to cover just down to 6hz, that one would need at 24hz). Fortunately, reciprocal PVG, and the manner in which PVG gives us more support to the fundamental frequency, and less reciprocal reinforcement to the harmonic distortion elements, and this helps us in our wacky endeavor for accurate of the LF/ULF playback in our HT's.
It's all good