I'm perfectly happy with my 1080p TV. I can't tell the difference to a 4K TV while sitting on my couch. Why would anyone want an 8K TV?
Boils down to bigger TVs. A 50inch tv at 1080p doesn't look so bad. But project it onto something much bigger and things start to look pixelated. 8k sounds like a nice resolution for people who have projectors with 3m diagonals.
it mostly looks pixelated because US uses mpeg2 and low bitrates.
It's possible that most people don't realize they are using displays without calibrating them. I assume that a compression system's assumptions of what's visible depends on the proper conversion of DAC input values to voltages. If these assumptions don't hold then artifacts are more visible.