I think one reason quadraphonic didn't catch on in the LP era in the early '70s is because LPs were already very musically satisfying and people weren't hankering for something more. The CD4/SQ format wars and extra hardware costs didn't help, either. LPs with the right cartridge could already fill the room with broadly dimensional sound.
In the digital age the opposite is true. Several things are missing from musical satisfaction in digital playback, and people are desperate to improve it--through cables, footers, pucks, racks...and more speakers and spatial cues (i.e., surround sound). One of the things that was missing in early digital and slow to make progress was imaging. I remember my first CD player (after years of listening to LPs) and I was shocked at how it sounded like threadbare music coming out of two separate speakers, whereas my LP rig threw a wide, deep, seamless soundstage.
Surround sound is one way to help fix that, since 2-channel analog playback--as much as I love it--won't be returning as the de facto standard.