From most users’ points of view, a lot of things the kernel does (e.g. a sound card driver) are non-critical so they’d prefer an error in that driver only killed that driver and not the whole kernel. Similarly, I’d be upset if a server rebooted because of a blip in its CD-ROM driver. And if you can just reload the module which errored, all the better.
It would be cool if kernel Rust could implement a panic handler which just killed the offending module, but I’m assuming from the discussion around panics that this isn’t possible.