Now that you mention it, there really has been like a year since rust has first been introduced the the kernel officially. I don't know if any parts of it have been written in rust as of now or whether new drivers have been made, but I suppose it's most likely still experimental in a way.
I agree that's very annoying sometimes but at the same time very beneficial for in-game performance as it greatly reduces the amount of computations the game has to do at runtime. If you have a powerful enough PC or the game isn't very demanding you can just disable shader pre-caching in steam settings and it shouldn't matter much but it's a real life saver for more demanding titles and imo worth all that wait.