Well....nerds is not really the right group. I'd say more the Geek Counter Culture as a whole.
You have a group of young people in roughly 1960 that, like all such groups, want to like "something different" then what their parents like.
Then you have East Asia full of magic, dragons, ninjas, samurai, martial arts and exotic weapons....and more. What's not to like.
So the youth grabbed on to it. Also, all the way up to about 2000.......it was very much a Geek Secret. And like all groups, Geeks love to have secrets. Unless you were a fan....and really, really, really put in a HUGE effort to watch Asia Media, it was unknown to you. Starting in the 70's a lot of East Asian Media was brought over to the USA....for kids. It's a long list. And...well, you need to remember the time.
Set the Wayback Machine for 1984. If you were a geek kid or teen or young adult....well there was NOT that much Geek Media(action/adventure/sicfi/fantasy/horror) for you to watch. Not that you could watch and access every day. There was the occasional movie, but after they left the theater they simply just vanished. Even when VCRs did start to come out not much was for Geeks. The "Geek Single Shelf" at Video Mart had like Star Wars, Alien and Planet of the Apes. TV was worse, the occasional Geek show was on maybe a couple years....and then just vanished. Maybe....MAYBE your local UHF channel got a couple copies and MAYBE played them at a time you could watch them....maybe.
It was the time of the Geek Void. And a couple clever people came along to fill this void, while making money. Japan alone was making all sorts of Geek Content starting in the 70's. And the thought was....well, lets bring it too America. And they did. G-Force, Star Blazers, Gundam, Voltron, Robotech and more. Geek Shows to fill the Geek Void. Martial arts, robots, ninjas, outer space, action, adventure and all. And even more then that....a LOT of the shows were very different then the stale American Media. And only a couple years after that came Cyberpunk and Anime. And Power Rangers and Pokemon....