Why the obsession with the lowest octave

From what is written in these forums and elsewhere see the following for instance.

Scroll down to the chart showing the even lowest instruments in this example recording rolling off very steeply at 40 Hz.

http://www.homerecordingconnection.com/news.php?action=view_story&id=154

It would appear that there is really very little to be heard between 20 and 40 Hz. Yet having true "full range" speakers is often the test of a great speaker. Does anyone beside me think that there is little to be gained by stretching the speakers bass performance below 30-40 cycles?
My own speakers make no apologies for going down to only 28 Hz and they are big floor standers JM Lab Electra 936s.