[kadoban]

Mostly it's a cost/ease thing. For the device to work correctly with no OS, the hardware inside has to be powerful enough to run all of the logic itself and it has to be coded up to do that.

If you wait until the OS is up, the device itself can offload a good amount of logic and processing to the device driver.

My bet would be that the main reason is that it's easier to find programmers who can write complex device drivers than it is to find ones who can write complex embedded firmware, and it's quicker/easier in general to write device drivers than firmware.

That and just 99% of people will never notice that it doesn't work outside of the OS, and of the rest, 99% will only be vaguely annoyed but not change brands over that.