They were highly used. OpenAI even included them in their RL Gym library back in the old days when they were still doing open research. But if you look at this leaderboard from 7 (yes, seven!) years ago [1], most of them were already solved way beyond human capabilities. But we didn't get a really useful general purpose algorithm out of it. As an AI researcher, I always considered Atari a fun academic exercise, but nothing more. Similar to how recognising characters using convnets was cool in the nineties and early 00s, but didn't give us general purpose image understanding. Only modern GPUs and massive training datasets did. Nowadays most cutting-edge RL game research focuses on much more advanced games like Minecraft which is thought to be better suited. But I'm pretty sure it's still not enough. Even role-playing GTA VI won't be. We probably need a pretty advanced physical simulation of the real world before we can get agents to handle the real world. But that means solving the problem of generating such an environment first, because you can't train on the actual real world due to the sample inefficiency of all current algorithms. Nvidia is doing some really interesting research in this direction by combining physics simulation and image generation models to simulate an environment, while getting accuracy and diversity at the same time into training data. But it still feels like some key ingredient is missing.
[1]https://github.com/cshenton/atari-leaderboard