Good question! I'm also not a Rust expert, but maybe that syntax would be considered unsafe in some situations?

I think the 'peripheral access crates' try to auto-generate those sorts of struct objects from SVD files, but you still need to obey Rust's ownership rules to get the advantage of its built-in memory safety.

So if a function needs to modify a peripheral's memory, it needs to claim mutable ownership of the relevant peripheral registers. That's a feature of the language which makes it 'safer', but the cost/benefit calculation is a bit different on embedded platforms. They have less memory, and static allocation is usually preferred.

Still, microcontrollers are getting faster quickly. You can even run Linux on some cortex-M4/M7 chips. The verbose syntax might be worthwhile if you're collaborating on complicated firmware.