While some of the more recent dance tracks may have intentionally included very LF content, not only weren't sub woofers that common in recording studios (not counting film mixers) but songs were often mixed to also sound good on auratones or similar tiny speakers, so any very low bass that was musically significant would surely include lots of harmonics to still be audible when played on typical playback systems. Unless the low bass was mixed dead center mono, it could also cause playback issues with those old round black vinyl thingees.
On the subject of unusual LF content, I seem to recall some seemingly low freq content on Kraftwerk's Autobahn, but never measured by me. Then there's telarc's 1812 overture with a mortar or whatever for the cannon fire.
I suspect too much LF, especially on older stuff is just sloppy engineering. In modern stuff who knows...
JR