Well, it means they can take a load off building the back story. Tell me it’s “2035”, and I imagine that things are mostly the same. The US still exists, Russia is still a mess, and Disney is still making Mickey Mouse crap.
Tell me it’s hundreds or thousands of years in the future, or even just “unspecified date”, and I have to wonder why all the cultural touchstones are the same. So you either have to explain why nothing has changed, or show how everything has changed. If all you really want to do is tell a good story about trying to stop a rouge Saturnian ring from destroying Washington D.C., that’s a pain in the ass.
A neutron star, which turns out to be inhabited by tiny sentient aliens who evolved under immense gravity, is discovered in the constellation Draco by Earth astronomers in 2020 in Robert L. Forward’s 1980 sf novel Dragon’s Egg.
They did that with Max Headroom, with the original idea of each episode being five minutes long. By the time it got to TV, the episodes were 30 minutes, which meant by the end of each epsiode we were already ten minutes past 20 minutes into the future.
I’m reminded of Streets of Fire, the 1984 action-musical-tragic-love-story “rock & roll fairy tale” movie where the title card simply says “Another time, another place” to describe its setting - a nameless American city with '50s cars and music, '70s urban blight, and '80s fashion sensibilities.
Besides dates, there’s a lot of sci-fi that was rendered obsolete by the collapse of the USSR. The Mickey Mouse Olympics by Thomas Sullivan for example was published in Omni in 1979, and involved a Disney-sponsored Olympics where the rivalry between the US and USSR was a core plot point. Nobody really expected the USSR to just go away like it did.
The book Armageddon 2419 introduced the character who became Buck Rogers. But his name was not William it was Anthony. The book never called him Buck either, but sometimes he was called Tony.
I remember watching a bootleg copy of Batman (the one with Michael Keaton) in Russia back in 1990. The guy I was with (a Russian and a good friend) couldn’t understand what '30s-style gangsters with Tommy guns were doing in what was supposed to be the present day, and why what was obviously NYC looked so Gothic.