but we do... 4 years after Rust, we got a first glimpse at Zig. Even today, there's a lot of people that believe that Zig would have been a better choice for the Linux kernel than Rust.

And the answer to "why now" is quite simple - Because of the whole Rust in kernel debate, people started scrutinizing the situation.

That makes no sense. It was much longer than 10 years before people considered C to be tech debt for example. Idk if it will be 10 years exactly, but we are seeing better languages emerging (Swift 6, Mojo, probably others) that provide the same safety guarantees and performance/use case profiles as Rust, but are vastly more ergonomic and lovely to use. I fear Linux was hasty integrating Rust because it will likely prevent them from integrating something better in the near future.