I think it's also important to note that on the game creation side, while there are a lot of great games that are made by gamers, there are also a ton of great or interesting games made by people who aren't gamers as well.
Toru Iwatani's Pac-Man, Tetsuya Takahashi's Xeno series, Yasuhiro Wada's Harvest Moon, Kazunori Yamauchi's Gran Turismo, Fumito Ueda's works, even Shigeru Miyamoto's creations to an extent come from places that are wholly separate from a gamer's typical influences. They come firstly from their individual passions for architecture, philosophy, gardening, cars, animation, art, etc. rather than other games.
It's precisely because they were outsiders with interests and passions pretty outside of the gaming realm that they were able to create games that were innovative and unique. Gamers making games isn't necessarily a bad thing, but they're inherently more likely to make something derivative just because they're usually looking toward other games as inspiration. Outsiders are able to look at problems with fresh eyes and come up with solutions and ideas that are different than what a more insulated group would come up with.
Granted, that’s not to say gamers don’t have interesting influences outside of games to draw from, but a lot of times they’re going to be pretty similar. Generally stuff a part of “nerd culture” like comics, manga, anime, role playing, science fiction, fantasy, etc. is a given.
However, I do think if games were still more insular and made primarily by gamers, it would be problematic in the long term. It kinda reminds me of that one quote from Studio Ghibli’s Hayao Miyazaki about the anime industry where he said he dislikes how modern anime is just made by otaku for otaku and doesn’t draw on actual life experiences like anime used to at its origin. Obviously it’s a little different for games as they don’t necessarily have to be a story telling medium, but I think it still has some application here.
But yeah, I think it’s easy to say the medium as a whole was better when it was more niche and insular, but honestly, I find myself utterly enraptured by lots of the games released even now. A lot of that may have to due with my age and my jack of all trades tastes when it comes to games, but I feel like there’s genuinely something for everyone nowadays for the most part if you’re willing to look for it.