It is just moving the complexity around.
In the old BIOS + ACPI days, the OS carries hardware specific hacks. These hack were buggy and hard to keep to day.
We (the community as a whole) decided it is better leave the hardware specific hacks to the hardware, UEFI was supposed to provide enough abstraction for all we need.
The result is, of course, the hacks with all its bugs are moved to the firmware.