Rather, I think they are not accessible enough. A picture on a wall, a movie or music can be experienced by hundreds or thousands of people all at once. Games in an art gallery have a much lower natural limit to the number of people who can interact with them simultaneously (at least in the same physical space). Sure, you can watch others do it, but that's not really the same thing (it's more like watching performance art than playing a game).
I have in fact been to art galleries which had interactive game-like exhibits. I basically never got to interact with them because, lo and behold, there was a long queue.
> Maybe actually go to an art gallery/museum sometime
This however is unfair and hypocritical re: assuming. I have been to many of the world's most celebrated museums of art, at least dozens of them, and have never personally seen video games in them firsthand.
I've seen and played games at the Cooper Hewitt Museum in NYC. Maybe I got lucky but it's one of like three museum visits I've ever done as a tourist in the city.