Is separating the hardware and software layers really a radical notion for embedded programming?
Unfortunately yes. Lots of embedded software development is done by folks without a software background. EE's and electronics technicians dabbling in firmware.
A bit of a generalisation, but I tend to find when a traditional EE writes firmware, they treat the firmware as controlling the hardware and are more direct with their instructions. i.e. if they need to set a gpio they will often do it directly rather than abstract it. So an EE will write gpio23 = 1, whilst a more software background person will create some type of function say, turn_amplifier_on which will then take the appropriate action.
For those tiny projects it doesn't matter too much. However it seems with demands for features/time to market we rely more on vendor supplied SDK's so this direct approach is becoming less common.
I do find the EE's to be great at bitbanging though, especially when timing is critical.