STM32L4R5 RTC BKPR writes are unsafe despite having no side effects

[bauen1]

The RTC backup registers for the STM32L4R5 are simply 32-bit memory and writing them has no other side effects, as such they should not require unsafe to write.
At least as far as I understand it so far.

In essence I want to be able to do:

rtc.bkpr[0].write(|w| w.bkp().bits(0));

Instead of:

rtc.bkpr[0].write(|w| unsafe { w.bkp().bits(0) });