This did not start at the iPod.

People have never been all about great sound, good has always been fine, except for a segment who either know about or have been taught (by us or others) that better is available.

Records gave us music, but with skips, pops and clicks. It didn't sound like live music unless you had upper level turntable, cartridge, amp, speakers.

8 Track tapes gave us convenience, but still lacking. Cassette tapes improved that, with the addition of Dolby, but still not there.

The Sony Elcaset (1/4", 3-3/4 ips in a cassette like shell) and DCC (Digital Compact Cassette were supposed to make cassettes sound like being in the studio. The public decided that the standard compact cassette was OK. These were still tape formats and didn't wow people.

The CD was revolutionary, because you could get studio quality in your living room. Early issues with masters that were made for LPs, digital filtering that needed time to get better, and such notwithstanding, CDs were a new super cool looking format (half the sell job) plus really high quality sound, and they took off.

Next was DVD Audio and Super Audio CDs, and once again, like a refinement for the lowly cassette, the public said, "Nah, the regular CDs sound pretty good to us."

You can talk about Beta, VHS, DVD (revolutionary like the CD), Blu-Ray, and UHD Players, but at a certain point, people are no longer impressed and are happy with Good Enough.

Ipods were revolutionary for the convenience factor and the storage was amazing. Those were more important to people than the sound quality, which depending on the bit rate, could be pretty good.

Their convenience factor, plus the huge price differential between them and music servers, again caused people to say again, Good Enough.

HD, 4k, 8k... At some point, they will say, Good Enough.