Probably because internet allows people to listen to music and watch stuff from a bunch of different eras. It doesn't feel retro because it never really went away. A lot of US TV series from the 90s and 2000s lasted forever too (CSI, NCIS etc). This is probably why people have this idea that today's content is 100% worse. We're always comparing today's shows with the classics.
In some ways I miss the 2000s. If you came from the Middle East in those years were absolute hell but culturally stuff was much more sensible. When the internet was new there really wasn't a good idea for how people should use it. So people just made stuff up as they went along. Because big social media juggernauts didn't exist there was more leeway for filmmakers, animators, mangaka, or game designers. Stuff wasn't as mass market and corporations weren't surveying Twitter for opinions. It's hard imaging some of the stuff made back then getting the greenlight today.
What does bug me is the way there is this culture of remembrance for things that happened in the 2000s (facebook, myspace emos) while other stuff has been memoryholed (e.g. 4chan antics, Iraq war). Flip phones, external computer speakers or RSS feeds were a thing everybody used but most ordinary people have completely forgotten about them.