Apparently, quad styli are still being manufactured, and there is a loyal group of quad enthusiasts. There are also people who collect 8 tracks, and I don't get that either, though I have a few.
That being said, some quad mixes are radically different, especially for albums that had lots of production and effects. For example, the quad mix of Pink Floyd's DSOTM is supposedly very different. There are completists who collect these for the differences, just as there are people who want to own a particular album in both stereo and mono. I'm just curious about how "Headhunters" sounds.
BTW, I still haven't completely embraced stereo, and prefer most albums in mono.