A lot of people used to debate this stuff, and I think it was just a lack of experience. There had only been so many turnovers in gamers (from being the main market to being a retro gamer) to that point. Think about it: if you got a 2600 in, say, 1980 at 6 years old, you were still the same guy playing a PS2 in 2000 at 26 years old. The entire history of consoles had happened to you, so the idea that people behind you would feel differently wasn't as obvious.
There are several ideas here.
People can be nostalgic things about their youth, like the music, movies, or books, but video gaming has also popped from being something the kids do to something the kids turned adults kept on doing. Its one thing to listen to the music of your youth, or even collect the toys you had as a kid, but its another to keep playing with those toys all the time and making it your hobby. We've done that with video games. We've said this thing from our childhood is not childish.
Very few people preserve things at that time. People need a new car, they generally sell off the old one. People needed a new radio, very often the old one got trashed. Those boardgames not fun anymore - sold them at a yard sale. (The exceptio to this are people looking to invest, but very often they preserve stuff very few people care about going forward. Very few people care about a 'Tickle Me Elmo -NIB' today) Because retrogaming is full of those former kids preserving their old stuff, we are here thinking about preserving even the stuff of today's kids 20-30 years from now.
Video gaming also has changed quickly with technology. Not many people play on their 1977 CB radio anymore, but here we are, gaming on our 1977 video game systems. Saving video gaming is, to a large extent, a challenge in technology and know how.
Video gaming is something we can preserve *and* share. If you want to preserve old vibrating football games, you preserve them. What you do really doesn't help anyone else. However, if you write a homebrew game, make a piece of hobbyist hardware, share your knowledge about 1980s video gaming, etc - you are helping an entire community.
Retro gamers are also concerned with saving not just the best games, but the most games, and preserving as best as we can the whole experience. In the 1970s, lots of books were published that not ever be reprinted or digitized and mostly no one really cares. Retro gamers want to save every game - the best, the worst, and everything in the middle - every VIC 20 game, every Channel F game, every BBC Micro game. We even want to save the magazines and books and the advertisements about the games!
Saving video games is also something a lone hobbyist can make their mark on. It also may not be taken so seriously outside video game channels, and there are laws that hamper saving it - also pushing saving video gaming into the hands of hobbyists. Who created emulation - hobbyists or professional archivists? Who has that 100% collector mentality that pushes them to preserve everything - hobbyists again.