Comment by eismcc

I worked on windows kernel team and my first real projects were ACPI 1 and 2 implementation. It's been a while and ACPI was well on its way when i got there, the story at the time was that huge gaps in BIOS were problem and we need to move it into the kernel. There was also a big push from the industry at the same time to use EFI to allow devices to have a pre-os experience (e.g. play DVDs) and not be dependent upon Windows for those.

Another memory I have for that time was that powermgmt was a big priority. So i suspect the ability for the OS to do that via ACPI was strategic - I wasn't involved in the decision making.